Merge pull request #29506 from pat/frozen-string-literals

Make ActiveSupport frozen-string-literal friendly.

65 files changed, 323 insertions, 323 deletions

diff --git a/actionmailer/test/base_test.rb b/actionmailer/test/base_test.rb
index ebb97078e6..06d4ea197c 100644
--- a/actionmailer/test/base_test.rb
+++ b/actionmailer/test/base_test.rb
@@ -120,7 +120,7 @@ class BaseTest < ActiveSupport::TestCase
     email = BaseMailer.attachment_with_hash
     assert_equal(1, email.attachments.length)
     assert_equal("invoice.jpg", email.attachments[0].filename)
-    expected = "\312\213\254\232)b"
+    expected = "\312\213\254\232)b".dup
     expected.force_encoding(Encoding::BINARY)
     assert_equal expected, email.attachments["invoice.jpg"].decoded
   end
@@ -129,7 +129,7 @@ class BaseTest < ActiveSupport::TestCase
     email = BaseMailer.attachment_with_hash_default_encoding
     assert_equal(1, email.attachments.length)
     assert_equal("invoice.jpg", email.attachments[0].filename)
-    expected = "\312\213\254\232)b"
+    expected = "\312\213\254\232)b".dup
     expected.force_encoding(Encoding::BINARY)
     assert_equal expected, email.attachments["invoice.jpg"].decoded
   end
diff --git a/actionpack/lib/action_controller/log_subscriber.rb b/actionpack/lib/action_controller/log_subscriber.rb
index d00fcbcd13..5d75393897 100644
--- a/actionpack/lib/action_controller/log_subscriber.rb
+++ b/actionpack/lib/action_controller/log_subscriber.rb
@@ -24,7 +24,7 @@ module ActionController
           exception_class_name = payload[:exception].first
           status = ActionDispatch::ExceptionWrapper.status_code_for_exception(exception_class_name)
         end
-        message = "Completed #{status} #{Rack::Utils::HTTP_STATUS_CODES[status]} in #{event.duration.round}ms"
+        message = "Completed #{status} #{Rack::Utils::HTTP_STATUS_CODES[status]} in #{event.duration.round}ms".dup
         message << " (#{additions.join(" | ".freeze)})" unless additions.empty?
         message << "\n\n" if defined?(Rails.env) && Rails.env.development?
 
diff --git a/actionpack/lib/action_dispatch/http/response.rb b/actionpack/lib/action_dispatch/http/response.rb
index 3c91677d55..4155c155da 100644
--- a/actionpack/lib/action_dispatch/http/response.rb
+++ b/actionpack/lib/action_dispatch/http/response.rb
@@ -103,7 +103,7 @@ module ActionDispatch # :nodoc:
 
       def body
         @str_body ||= begin
-          buf = ""
+          buf = "".dup
           each { |chunk| buf << chunk }
           buf
         end
diff --git a/actionpack/lib/action_dispatch/journey/router/utils.rb b/actionpack/lib/action_dispatch/journey/router/utils.rb
index 6d400f3364..1ac86d10d6 100644
--- a/actionpack/lib/action_dispatch/journey/router/utils.rb
+++ b/actionpack/lib/action_dispatch/journey/router/utils.rb
@@ -14,11 +14,11 @@ module ActionDispatch
         #   normalize_path("/%ab")  # => "/%AB"
         def self.normalize_path(path)
           encoding = path.encoding
-          path = "/#{path}"
+          path = "/#{path}".dup
           path.squeeze!("/".freeze)
           path.sub!(%r{/+\Z}, "".freeze)
           path.gsub!(/(%[a-f0-9]{2})/) { $1.upcase }
-          path = "/" if path == "".freeze
+          path = "/".dup if path == "".freeze
           path.force_encoding(encoding)
           path
         end
@@ -29,7 +29,7 @@ module ActionDispatch
           ENCODE   = "%%%02X".freeze
           US_ASCII = Encoding::US_ASCII
           UTF_8    = Encoding::UTF_8
-          EMPTY    = "".force_encoding(US_ASCII).freeze
+          EMPTY    = "".dup.force_encoding(US_ASCII).freeze
           DEC2HEX  = (0..255).to_a.map { |i| ENCODE % i }.map { |s| s.force_encoding(US_ASCII) }
 
           ALPHA = "a-zA-Z".freeze
diff --git a/actionpack/lib/action_dispatch/testing/assertions/response.rb b/actionpack/lib/action_dispatch/testing/assertions/response.rb
index 1baf979ac9..749f2eab57 100644
--- a/actionpack/lib/action_dispatch/testing/assertions/response.rb
+++ b/actionpack/lib/action_dispatch/testing/assertions/response.rb
@@ -79,7 +79,7 @@ module ActionDispatch
         def generate_response_message(expected, actual = @response.response_code)
           "Expected response to be a <#{code_with_name(expected)}>,"\
           " but was a <#{code_with_name(actual)}>"
-            .concat(location_if_redirected).concat(response_body_if_short)
+            .dup.concat(location_if_redirected).concat(response_body_if_short)
         end
 
         def response_body_if_short
diff --git a/actionview/lib/action_view/helpers/date_helper.rb b/actionview/lib/action_view/helpers/date_helper.rb
index 3f43465aa4..d28eec88a1 100644
--- a/actionview/lib/action_view/helpers/date_helper.rb
+++ b/actionview/lib/action_view/helpers/date_helper.rb
@@ -1007,7 +1007,7 @@ module ActionView
           select_options[:disabled] = "disabled" if @options[:disabled]
           select_options[:class] = css_class_attribute(type, select_options[:class], @options[:with_css_classes]) if @options[:with_css_classes]
 
-          select_html = "\n"
+          select_html = "\n".dup
           select_html << content_tag("option".freeze, "", value: "") + "\n" if @options[:include_blank]
           select_html << prompt_option_tag(type, @options[:prompt]) + "\n" if @options[:prompt]
           select_html << select_options_as_html
@@ -1089,7 +1089,7 @@ module ActionView
         # Given an ordering of datetime components, create the selection HTML
         # and join them with their appropriate separators.
         def build_selects_from_types(order)
-          select = ""
+          select = "".dup
           first_visible = order.find { |type| !@options[:"discard_#{type}"] }
           order.reverse_each do |type|
             separator = separator(type) unless type == first_visible # don't add before first visible field
diff --git a/actionview/lib/action_view/helpers/javascript_helper.rb b/actionview/lib/action_view/helpers/javascript_helper.rb
index 22e1e74ad6..6ba70ec081 100644
--- a/actionview/lib/action_view/helpers/javascript_helper.rb
+++ b/actionview/lib/action_view/helpers/javascript_helper.rb
@@ -13,8 +13,8 @@ module ActionView
         "'"     => "\\'"
       }
 
-      JS_ESCAPE_MAP["\342\200\250".force_encoding(Encoding::UTF_8).encode!] = "&#x2028;"
-      JS_ESCAPE_MAP["\342\200\251".force_encoding(Encoding::UTF_8).encode!] = "&#x2029;"
+      JS_ESCAPE_MAP["\342\200\250".dup.force_encoding(Encoding::UTF_8).encode!] = "&#x2028;"
+      JS_ESCAPE_MAP["\342\200\251".dup.force_encoding(Encoding::UTF_8).encode!] = "&#x2029;"
 
       # Escapes carriage returns and single and double quotes for JavaScript segments.
       #
diff --git a/actionview/lib/action_view/helpers/translation_helper.rb b/actionview/lib/action_view/helpers/translation_helper.rb
index cc928f2b7a..24d1f34c5a 100644
--- a/actionview/lib/action_view/helpers/translation_helper.rb
+++ b/actionview/lib/action_view/helpers/translation_helper.rb
@@ -95,7 +95,7 @@ module ActionView
           raise e if raise_error
 
           keys = I18n.normalize_keys(e.locale, e.key, e.options[:scope])
-          title = "translation missing: #{keys.join('.')}"
+          title = "translation missing: #{keys.join('.')}".dup
 
           interpolations = options.except(:default, :scope)
           if interpolations.any?
diff --git a/actionview/lib/action_view/log_subscriber.rb b/actionview/lib/action_view/log_subscriber.rb
index ab8ec0aa42..613be2b877 100644
--- a/actionview/lib/action_view/log_subscriber.rb
+++ b/actionview/lib/action_view/log_subscriber.rb
@@ -14,7 +14,7 @@ module ActionView
 
     def render_template(event)
       info do
-        message = "  Rendered #{from_rails_root(event.payload[:identifier])}"
+        message = "  Rendered #{from_rails_root(event.payload[:identifier])}".dup
         message << " within #{from_rails_root(event.payload[:layout])}" if event.payload[:layout]
         message << " (#{event.duration.round(1)}ms)"
       end
@@ -22,7 +22,7 @@ module ActionView
 
     def render_partial(event)
       info do
-        message = "  Rendered #{from_rails_root(event.payload[:identifier])}"
+        message = "  Rendered #{from_rails_root(event.payload[:identifier])}".dup
         message << " within #{from_rails_root(event.payload[:layout])}" if event.payload[:layout]
         message << " (#{event.duration.round(1)}ms)"
         message << " #{cache_message(event.payload)}" unless event.payload[:cache_hit].nil?
diff --git a/actionview/lib/action_view/template.rb b/actionview/lib/action_view/template.rb
index b0e2f1e54e..3f2546664e 100644
--- a/actionview/lib/action_view/template.rb
+++ b/actionview/lib/action_view/template.rb
@@ -282,7 +282,7 @@ module ActionView
 
         # Make sure that the resulting String to be eval'd is in the
         # encoding of the code
-        source = <<-end_src
+        source = <<-end_src.dup
           def #{method_name}(local_assigns, output_buffer)
             _old_virtual_path, @virtual_path = @virtual_path, #{@virtual_path.inspect};_old_output_buffer = @output_buffer;#{locals_code};#{code}
           ensure
@@ -329,12 +329,12 @@ module ActionView
         locals = locals.grep(/\A@?(?![A-Z0-9])(?:[[:alnum:]_]|[^\0-\177])+\z/)
 
         # Double assign to suppress the dreaded 'assigned but unused variable' warning
-        locals.each_with_object("") { |key, code| code << "#{key} = #{key} = local_assigns[:#{key}];" }
+        locals.each_with_object("".dup) { |key, code| code << "#{key} = #{key} = local_assigns[:#{key}];" }
       end
 
       def method_name
         @method_name ||= begin
-          m = "_#{identifier_method_name}__#{@identifier.hash}_#{__id__}"
+          m = "_#{identifier_method_name}__#{@identifier.hash}_#{__id__}".dup
           m.tr!("-".freeze, "_".freeze)
           m
         end
diff --git a/actionview/lib/action_view/template/resolver.rb b/actionview/lib/action_view/template/resolver.rb
index 75ea4d31f5..65f8be26a0 100644
--- a/actionview/lib/action_view/template/resolver.rb
+++ b/actionview/lib/action_view/template/resolver.rb
@@ -14,7 +14,7 @@ module ActionView
       alias_method :partial?, :partial
 
       def self.build(name, prefix, partial)
-        virtual = ""
+        virtual = "".dup
         virtual << "#{prefix}/" unless prefix.empty?
         virtual << (partial ? "_#{name}" : name)
         new name, prefix, partial, virtual
diff --git a/actionview/lib/action_view/test_case.rb b/actionview/lib/action_view/test_case.rb
index 80403799ab..424a86ba3e 100644
--- a/actionview/lib/action_view/test_case.rb
+++ b/actionview/lib/action_view/test_case.rb
@@ -104,7 +104,7 @@ module ActionView
         # empty string ensures buffer has UTF-8 encoding as
         # new without arguments returns ASCII-8BIT encoded buffer like String#new
         @output_buffer = ActiveSupport::SafeBuffer.new ""
-        @rendered = ""
+        @rendered = "".dup
 
         make_test_case_available_to_view!
         say_no_to_protect_against_forgery!
diff --git a/actionview/lib/action_view/testing/resolvers.rb b/actionview/lib/action_view/testing/resolvers.rb
index 3188526b63..b2d3e10690 100644
--- a/actionview/lib/action_view/testing/resolvers.rb
+++ b/actionview/lib/action_view/testing/resolvers.rb
@@ -20,7 +20,7 @@ module ActionView #:nodoc:
     private
 
       def query(path, exts, _, _)
-        query = ""
+        query = "".dup
         EXTENSIONS.each_key do |ext|
           query << "(" << exts[ext].map { |e| e && Regexp.escape(".#{e}") }.join("|") << "|)"
         end
diff --git a/actionview/test/activerecord/form_helper_activerecord_test.rb b/actionview/test/activerecord/form_helper_activerecord_test.rb
index 3b314588c7..9949c3fde0 100644
--- a/actionview/test/activerecord/form_helper_activerecord_test.rb
+++ b/actionview/test/activerecord/form_helper_activerecord_test.rb
@@ -55,7 +55,7 @@ class FormHelperActiveRecordTest < ActionView::TestCase
   private
 
     def hidden_fields(method = nil)
-      txt = %{<input name="utf8" type="hidden" value="&#x2713;" />}
+      txt = %{<input name="utf8" type="hidden" value="&#x2713;" />}.dup
 
       if method && !%w(get post).include?(method.to_s)
         txt << %{<input name="_method" type="hidden" value="#{method}" />}
@@ -65,7 +65,7 @@ class FormHelperActiveRecordTest < ActionView::TestCase
     end
 
     def form_text(action = "/", id = nil, html_class = nil, remote = nil, multipart = nil, method = nil)
-      txt =  %{<form accept-charset="UTF-8" action="#{action}"}
+      txt =  %{<form accept-charset="UTF-8" action="#{action}"}.dup
       txt << %{ enctype="multipart/form-data"} if multipart
       txt << %{ data-remote="true"} if remote
       txt << %{ class="#{html_class}"} if html_class
diff --git a/actionview/test/fixtures/ruby_template.ruby b/actionview/test/fixtures/ruby_template.ruby
index 5097bce47c..93334610a8 100644
--- a/actionview/test/fixtures/ruby_template.ruby
+++ b/actionview/test/fixtures/ruby_template.ruby
@@ -1,2 +1,2 @@
-body = ""
+body = "".dup
 body << ["Hello", "from", "Ruby", "code"].join(" ")
diff --git a/actionview/test/template/atom_feed_helper_test.rb b/actionview/test/template/atom_feed_helper_test.rb
index 7304b769a4..7fa5e042fb 100644
--- a/actionview/test/template/atom_feed_helper_test.rb
+++ b/actionview/test/template/atom_feed_helper_test.rb
@@ -194,7 +194,7 @@ class ScrollsController < ActionController::Base
   FEEDS["provide_builder"] = <<-'EOT'
           # we pass in the new_xml to the helper so it doesn't
           # call anything on the original builder
-          new_xml = Builder::XmlMarkup.new(:target=>'')
+          new_xml = Builder::XmlMarkup.new(:target=>''.dup)
           atom_feed(:xml => new_xml) do |feed|
             feed.title("My great blog!")
             feed.updated(@scrolls.first.created_at)
diff --git a/actionview/test/template/date_helper_test.rb b/actionview/test/template/date_helper_test.rb
index b667303318..b9b8194e69 100644
--- a/actionview/test/template/date_helper_test.rb
+++ b/actionview/test/template/date_helper_test.rb
@@ -214,7 +214,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_day
-    expected = %(<select id="date_day" name="date[day]">\n)
+    expected = %(<select id="date_day" name="date[day]">\n).dup
     expected << %(<option value="1">1</option>\n<option value="2">2</option>\n<option value="3">3</option>\n<option value="4">4</option>\n<option value="5">5</option>\n<option value="6">6</option>\n<option value="7">7</option>\n<option value="8">8</option>\n<option value="9">9</option>\n<option value="10">10</option>\n<option value="11">11</option>\n<option value="12">12</option>\n<option value="13">13</option>\n<option value="14">14</option>\n<option value="15">15</option>\n<option value="16" selected="selected">16</option>\n<option value="17">17</option>\n<option value="18">18</option>\n<option value="19">19</option>\n<option value="20">20</option>\n<option value="21">21</option>\n<option value="22">22</option>\n<option value="23">23</option>\n<option value="24">24</option>\n<option value="25">25</option>\n<option value="26">26</option>\n<option value="27">27</option>\n<option value="28">28</option>\n<option value="29">29</option>\n<option value="30">30</option>\n<option value="31">31</option>\n)
     expected << "</select>\n"
 
@@ -223,7 +223,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_day_with_blank
-    expected = %(<select id="date_day" name="date[day]">\n)
+    expected = %(<select id="date_day" name="date[day]">\n).dup
     expected << %(<option value=""></option>\n<option value="1">1</option>\n<option value="2">2</option>\n<option value="3">3</option>\n<option value="4">4</option>\n<option value="5">5</option>\n<option value="6">6</option>\n<option value="7">7</option>\n<option value="8">8</option>\n<option value="9">9</option>\n<option value="10">10</option>\n<option value="11">11</option>\n<option value="12">12</option>\n<option value="13">13</option>\n<option value="14">14</option>\n<option value="15">15</option>\n<option value="16" selected="selected">16</option>\n<option value="17">17</option>\n<option value="18">18</option>\n<option value="19">19</option>\n<option value="20">20</option>\n<option value="21">21</option>\n<option value="22">22</option>\n<option value="23">23</option>\n<option value="24">24</option>\n<option value="25">25</option>\n<option value="26">26</option>\n<option value="27">27</option>\n<option value="28">28</option>\n<option value="29">29</option>\n<option value="30">30</option>\n<option value="31">31</option>\n)
     expected << "</select>\n"
 
@@ -232,7 +232,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_day_nil_with_blank
-    expected = %(<select id="date_day" name="date[day]">\n)
+    expected = %(<select id="date_day" name="date[day]">\n).dup
     expected << %(<option value=""></option>\n<option value="1">1</option>\n<option value="2">2</option>\n<option value="3">3</option>\n<option value="4">4</option>\n<option value="5">5</option>\n<option value="6">6</option>\n<option value="7">7</option>\n<option value="8">8</option>\n<option value="9">9</option>\n<option value="10">10</option>\n<option value="11">11</option>\n<option value="12">12</option>\n<option value="13">13</option>\n<option value="14">14</option>\n<option value="15">15</option>\n<option value="16">16</option>\n<option value="17">17</option>\n<option value="18">18</option>\n<option value="19">19</option>\n<option value="20">20</option>\n<option value="21">21</option>\n<option value="22">22</option>\n<option value="23">23</option>\n<option value="24">24</option>\n<option value="25">25</option>\n<option value="26">26</option>\n<option value="27">27</option>\n<option value="28">28</option>\n<option value="29">29</option>\n<option value="30">30</option>\n<option value="31">31</option>\n)
     expected << "</select>\n"
 
@@ -240,7 +240,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_day_with_two_digit_numbers
-    expected = %(<select id="date_day" name="date[day]">\n)
+    expected = %(<select id="date_day" name="date[day]">\n).dup
     expected << %(<option value="1">01</option>\n<option selected="selected" value="2">02</option>\n<option value="3">03</option>\n<option value="4">04</option>\n<option value="5">05</option>\n<option value="6">06</option>\n<option value="7">07</option>\n<option value="8">08</option>\n<option value="9">09</option>\n<option value="10">10</option>\n<option value="11">11</option>\n<option value="12">12</option>\n<option value="13">13</option>\n<option value="14">14</option>\n<option value="15">15</option>\n<option value="16">16</option>\n<option value="17">17</option>\n<option value="18">18</option>\n<option value="19">19</option>\n<option value="20">20</option>\n<option value="21">21</option>\n<option value="22">22</option>\n<option value="23">23</option>\n<option value="24">24</option>\n<option value="25">25</option>\n<option value="26">26</option>\n<option value="27">27</option>\n<option value="28">28</option>\n<option value="29">29</option>\n<option value="30">30</option>\n<option value="31">31</option>\n)
     expected << "</select>\n"
 
@@ -249,7 +249,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_day_with_html_options
-    expected = %(<select id="date_day" name="date[day]" class="selector">\n)
+    expected = %(<select id="date_day" name="date[day]" class="selector">\n).dup
     expected << %(<option value="1">1</option>\n<option value="2">2</option>\n<option value="3">3</option>\n<option value="4">4</option>\n<option value="5">5</option>\n<option value="6">6</option>\n<option value="7">7</option>\n<option value="8">8</option>\n<option value="9">9</option>\n<option value="10">10</option>\n<option value="11">11</option>\n<option value="12">12</option>\n<option value="13">13</option>\n<option value="14">14</option>\n<option value="15">15</option>\n<option value="16" selected="selected">16</option>\n<option value="17">17</option>\n<option value="18">18</option>\n<option value="19">19</option>\n<option value="20">20</option>\n<option value="21">21</option>\n<option value="22">22</option>\n<option value="23">23</option>\n<option value="24">24</option>\n<option value="25">25</option>\n<option value="26">26</option>\n<option value="27">27</option>\n<option value="28">28</option>\n<option value="29">29</option>\n<option value="30">30</option>\n<option value="31">31</option>\n)
     expected << "</select>\n"
 
@@ -258,7 +258,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_day_with_default_prompt
-    expected = %(<select id="date_day" name="date[day]">\n)
+    expected = %(<select id="date_day" name="date[day]">\n).dup
     expected << %(<option value="">Day</option>\n<option value="1">1</option>\n<option value="2">2</option>\n<option value="3">3</option>\n<option value="4">4</option>\n<option value="5">5</option>\n<option value="6">6</option>\n<option value="7">7</option>\n<option value="8">8</option>\n<option value="9">9</option>\n<option value="10">10</option>\n<option value="11">11</option>\n<option value="12">12</option>\n<option value="13">13</option>\n<option value="14">14</option>\n<option value="15">15</option>\n<option value="16" selected="selected">16</option>\n<option value="17">17</option>\n<option value="18">18</option>\n<option value="19">19</option>\n<option value="20">20</option>\n<option value="21">21</option>\n<option value="22">22</option>\n<option value="23">23</option>\n<option value="24">24</option>\n<option value="25">25</option>\n<option value="26">26</option>\n<option value="27">27</option>\n<option value="28">28</option>\n<option value="29">29</option>\n<option value="30">30</option>\n<option value="31">31</option>\n)
     expected << "</select>\n"
 
@@ -266,7 +266,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_day_with_custom_prompt
-    expected = %(<select id="date_day" name="date[day]">\n)
+    expected = %(<select id="date_day" name="date[day]">\n).dup
     expected << %(<option value="">Choose day</option>\n<option value="1">1</option>\n<option value="2">2</option>\n<option value="3">3</option>\n<option value="4">4</option>\n<option value="5">5</option>\n<option value="6">6</option>\n<option value="7">7</option>\n<option value="8">8</option>\n<option value="9">9</option>\n<option value="10">10</option>\n<option value="11">11</option>\n<option value="12">12</option>\n<option value="13">13</option>\n<option value="14">14</option>\n<option value="15">15</option>\n<option value="16" selected="selected">16</option>\n<option value="17">17</option>\n<option value="18">18</option>\n<option value="19">19</option>\n<option value="20">20</option>\n<option value="21">21</option>\n<option value="22">22</option>\n<option value="23">23</option>\n<option value="24">24</option>\n<option value="25">25</option>\n<option value="26">26</option>\n<option value="27">27</option>\n<option value="28">28</option>\n<option value="29">29</option>\n<option value="30">30</option>\n<option value="31">31</option>\n)
     expected << "</select>\n"
 
@@ -274,7 +274,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_day_with_generic_with_css_classes
-    expected = %(<select id="date_day" name="date[day]" class="day">\n)
+    expected = %(<select id="date_day" name="date[day]" class="day">\n).dup
     expected << %(<option value="1">1</option>\n<option value="2">2</option>\n<option value="3">3</option>\n<option value="4">4</option>\n<option value="5">5</option>\n<option value="6">6</option>\n<option value="7">7</option>\n<option value="8">8</option>\n<option value="9">9</option>\n<option value="10">10</option>\n<option value="11">11</option>\n<option value="12">12</option>\n<option value="13">13</option>\n<option value="14">14</option>\n<option value="15">15</option>\n<option value="16" selected="selected">16</option>\n<option value="17">17</option>\n<option value="18">18</option>\n<option value="19">19</option>\n<option value="20">20</option>\n<option value="21">21</option>\n<option value="22">22</option>\n<option value="23">23</option>\n<option value="24">24</option>\n<option value="25">25</option>\n<option value="26">26</option>\n<option value="27">27</option>\n<option value="28">28</option>\n<option value="29">29</option>\n<option value="30">30</option>\n<option value="31">31</option>\n)
     expected << "</select>\n"
 
@@ -282,7 +282,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_day_with_custom_with_css_classes
-    expected = %(<select id="date_day" name="date[day]" class="my-day">\n)
+    expected = %(<select id="date_day" name="date[day]" class="my-day">\n).dup
     expected << %(<option value="1">1</option>\n<option value="2">2</option>\n<option value="3">3</option>\n<option value="4">4</option>\n<option value="5">5</option>\n<option value="6">6</option>\n<option value="7">7</option>\n<option value="8">8</option>\n<option value="9">9</option>\n<option value="10">10</option>\n<option value="11">11</option>\n<option value="12">12</option>\n<option value="13">13</option>\n<option value="14">14</option>\n<option value="15">15</option>\n<option value="16" selected="selected">16</option>\n<option value="17">17</option>\n<option value="18">18</option>\n<option value="19">19</option>\n<option value="20">20</option>\n<option value="21">21</option>\n<option value="22">22</option>\n<option value="23">23</option>\n<option value="24">24</option>\n<option value="25">25</option>\n<option value="26">26</option>\n<option value="27">27</option>\n<option value="28">28</option>\n<option value="29">29</option>\n<option value="30">30</option>\n<option value="31">31</option>\n)
     expected << "</select>\n"
 
@@ -290,7 +290,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_month
-    expected = %(<select id="date_month" name="date[month]">\n)
+    expected = %(<select id="date_month" name="date[month]">\n).dup
     expected << %(<option value="1">January</option>\n<option value="2">February</option>\n<option value="3">March</option>\n<option value="4">April</option>\n<option value="5">May</option>\n<option value="6">June</option>\n<option value="7">July</option>\n<option value="8" selected="selected">August</option>\n<option value="9">September</option>\n<option value="10">October</option>\n<option value="11">November</option>\n<option value="12">December</option>\n)
     expected << "</select>\n"
 
@@ -299,7 +299,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_month_with_two_digit_numbers
-    expected = %(<select id="date_month" name="date[month]">\n)
+    expected = %(<select id="date_month" name="date[month]">\n).dup
     expected << %(<option value="1">01</option>\n<option value="2">02</option>\n<option value="3">03</option>\n<option value="4">04</option>\n<option value="5">05</option>\n<option value="6">06</option>\n<option value="7">07</option>\n<option value="8" selected="selected">08</option>\n<option value="9">09</option>\n<option value="10">10</option>\n<option value="11">11</option>\n<option value="12">12</option>\n)
     expected << "</select>\n"
 
@@ -308,7 +308,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_month_with_disabled
-    expected = %(<select id="date_month" name="date[month]" disabled="disabled">\n)
+    expected = %(<select id="date_month" name="date[month]" disabled="disabled">\n).dup
     expected << %(<option value="1">January</option>\n<option value="2">February</option>\n<option value="3">March</option>\n<option value="4">April</option>\n<option value="5">May</option>\n<option value="6">June</option>\n<option value="7">July</option>\n<option value="8" selected="selected">August</option>\n<option value="9">September</option>\n<option value="10">October</option>\n<option value="11">November</option>\n<option value="12">December</option>\n)
     expected << "</select>\n"
 
@@ -317,7 +317,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_month_with_field_name_override
-    expected = %(<select id="date_mois" name="date[mois]">\n)
+    expected = %(<select id="date_mois" name="date[mois]">\n).dup
     expected << %(<option value="1">January</option>\n<option value="2">February</option>\n<option value="3">March</option>\n<option value="4">April</option>\n<option value="5">May</option>\n<option value="6">June</option>\n<option value="7">July</option>\n<option value="8" selected="selected">August</option>\n<option value="9">September</option>\n<option value="10">October</option>\n<option value="11">November</option>\n<option value="12">December</option>\n)
     expected << "</select>\n"
 
@@ -326,7 +326,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_month_with_blank
-    expected = %(<select id="date_month" name="date[month]">\n)
+    expected = %(<select id="date_month" name="date[month]">\n).dup
     expected << %(<option value=""></option>\n<option value="1">January</option>\n<option value="2">February</option>\n<option value="3">March</option>\n<option value="4">April</option>\n<option value="5">May</option>\n<option value="6">June</option>\n<option value="7">July</option>\n<option value="8" selected="selected">August</option>\n<option value="9">September</option>\n<option value="10">October</option>\n<option value="11">November</option>\n<option value="12">December</option>\n)
     expected << "</select>\n"
 
@@ -335,7 +335,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_month_nil_with_blank
-    expected = %(<select id="date_month" name="date[month]">\n)
+    expected = %(<select id="date_month" name="date[month]">\n).dup
     expected << %(<option value=""></option>\n<option value="1">January</option>\n<option value="2">February</option>\n<option value="3">March</option>\n<option value="4">April</option>\n<option value="5">May</option>\n<option value="6">June</option>\n<option value="7">July</option>\n<option value="8">August</option>\n<option value="9">September</option>\n<option value="10">October</option>\n<option value="11">November</option>\n<option value="12">December</option>\n)
     expected << "</select>\n"
 
@@ -343,7 +343,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_month_with_numbers
-    expected = %(<select id="date_month" name="date[month]">\n)
+    expected = %(<select id="date_month" name="date[month]">\n).dup
     expected << %(<option value="1">1</option>\n<option value="2">2</option>\n<option value="3">3</option>\n<option value="4">4</option>\n<option value="5">5</option>\n<option value="6">6</option>\n<option value="7">7</option>\n<option value="8" selected="selected">8</option>\n<option value="9">9</option>\n<option value="10">10</option>\n<option value="11">11</option>\n<option value="12">12</option>\n)
     expected << "</select>\n"
 
@@ -352,7 +352,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_month_with_numbers_and_names
-    expected = %(<select id="date_month" name="date[month]">\n)
+    expected = %(<select id="date_month" name="date[month]">\n).dup
     expected << %(<option value="1">1 - January</option>\n<option value="2">2 - February</option>\n<option value="3">3 - March</option>\n<option value="4">4 - April</option>\n<option value="5">5 - May</option>\n<option value="6">6 - June</option>\n<option value="7">7 - July</option>\n<option value="8" selected="selected">8 - August</option>\n<option value="9">9 - September</option>\n<option value="10">10 - October</option>\n<option value="11">11 - November</option>\n<option value="12">12 - December</option>\n)
     expected << "</select>\n"
 
@@ -361,7 +361,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_month_with_format_string
-    expected = %(<select id="date_month" name="date[month]">\n)
+    expected = %(<select id="date_month" name="date[month]">\n).dup
     expected << %(<option value="1">January (01)</option>\n<option value="2">February (02)</option>\n<option value="3">March (03)</option>\n<option value="4">April (04)</option>\n<option value="5">May (05)</option>\n<option value="6">June (06)</option>\n<option value="7">July (07)</option>\n<option value="8" selected="selected">August (08)</option>\n<option value="9">September (09)</option>\n<option value="10">October (10)</option>\n<option value="11">November (11)</option>\n<option value="12">December (12)</option>\n)
     expected << "</select>\n"
 
@@ -371,7 +371,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_month_with_numbers_and_names_with_abbv
-    expected = %(<select id="date_month" name="date[month]">\n)
+    expected = %(<select id="date_month" name="date[month]">\n).dup
     expected << %(<option value="1">1 - Jan</option>\n<option value="2">2 - Feb</option>\n<option value="3">3 - Mar</option>\n<option value="4">4 - Apr</option>\n<option value="5">5 - May</option>\n<option value="6">6 - Jun</option>\n<option value="7">7 - Jul</option>\n<option value="8" selected="selected">8 - Aug</option>\n<option value="9">9 - Sep</option>\n<option value="10">10 - Oct</option>\n<option value="11">11 - Nov</option>\n<option value="12">12 - Dec</option>\n)
     expected << "</select>\n"
 
@@ -380,7 +380,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_month_with_abbv
-    expected = %(<select id="date_month" name="date[month]">\n)
+    expected = %(<select id="date_month" name="date[month]">\n).dup
     expected << %(<option value="1">Jan</option>\n<option value="2">Feb</option>\n<option value="3">Mar</option>\n<option value="4">Apr</option>\n<option value="5">May</option>\n<option value="6">Jun</option>\n<option value="7">Jul</option>\n<option value="8" selected="selected">Aug</option>\n<option value="9">Sep</option>\n<option value="10">Oct</option>\n<option value="11">Nov</option>\n<option value="12">Dec</option>\n)
     expected << "</select>\n"
 
@@ -391,7 +391,7 @@ class DateHelperTest < ActionView::TestCase
   def test_select_month_with_custom_names
     month_names = %w(nil Januar Februar Marts April Maj Juni Juli August September Oktober November December)
 
-    expected = %(<select id="date_month" name="date[month]">\n)
+    expected = %(<select id="date_month" name="date[month]">\n).dup
     1.upto(12) { |month| expected << %(<option value="#{month}"#{' selected="selected"' if month == 8}>#{month_names[month]}</option>\n) }
     expected << "</select>\n"
 
@@ -402,7 +402,7 @@ class DateHelperTest < ActionView::TestCase
   def test_select_month_with_zero_indexed_custom_names
     month_names = %w(Januar Februar Marts April Maj Juni Juli August September Oktober November December)
 
-    expected = %(<select id="date_month" name="date[month]">\n)
+    expected = %(<select id="date_month" name="date[month]">\n).dup
     1.upto(12) { |month| expected << %(<option value="#{month}"#{' selected="selected"' if month == 8}>#{month_names[month - 1]}</option>\n) }
     expected << "</select>\n"
 
@@ -419,7 +419,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_month_with_html_options
-    expected = %(<select id="date_month" name="date[month]" class="selector" accesskey="M">\n)
+    expected = %(<select id="date_month" name="date[month]" class="selector" accesskey="M">\n).dup
     expected << %(<option value="1">January</option>\n<option value="2">February</option>\n<option value="3">March</option>\n<option value="4">April</option>\n<option value="5">May</option>\n<option value="6">June</option>\n<option value="7">July</option>\n<option value="8" selected="selected">August</option>\n<option value="9">September</option>\n<option value="10">October</option>\n<option value="11">November</option>\n<option value="12">December</option>\n)
     expected << "</select>\n"
 
@@ -427,7 +427,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_month_with_default_prompt
-    expected = %(<select id="date_month" name="date[month]">\n)
+    expected = %(<select id="date_month" name="date[month]">\n).dup
     expected << %(<option value="">Month</option>\n<option value="1">January</option>\n<option value="2">February</option>\n<option value="3">March</option>\n<option value="4">April</option>\n<option value="5">May</option>\n<option value="6">June</option>\n<option value="7">July</option>\n<option value="8" selected="selected">August</option>\n<option value="9">September</option>\n<option value="10">October</option>\n<option value="11">November</option>\n<option value="12">December</option>\n)
     expected << "</select>\n"
 
@@ -435,7 +435,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_month_with_custom_prompt
-    expected = %(<select id="date_month" name="date[month]">\n)
+    expected = %(<select id="date_month" name="date[month]">\n).dup
     expected << %(<option value="">Choose month</option>\n<option value="1">January</option>\n<option value="2">February</option>\n<option value="3">March</option>\n<option value="4">April</option>\n<option value="5">May</option>\n<option value="6">June</option>\n<option value="7">July</option>\n<option value="8" selected="selected">August</option>\n<option value="9">September</option>\n<option value="10">October</option>\n<option value="11">November</option>\n<option value="12">December</option>\n)
     expected << "</select>\n"
 
@@ -443,7 +443,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_month_with_generic_with_css_classes
-    expected = %(<select id="date_month" name="date[month]" class="month">\n)
+    expected = %(<select id="date_month" name="date[month]" class="month">\n).dup
     expected << %(<option value="1">January</option>\n<option value="2">February</option>\n<option value="3">March</option>\n<option value="4">April</option>\n<option value="5">May</option>\n<option value="6">June</option>\n<option value="7">July</option>\n<option value="8" selected="selected">August</option>\n<option value="9">September</option>\n<option value="10">October</option>\n<option value="11">November</option>\n<option value="12">December</option>\n)
     expected << "</select>\n"
 
@@ -451,7 +451,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_month_with_custom_with_css_classes
-    expected = %(<select id="date_month" name="date[month]" class="my-month">\n)
+    expected = %(<select id="date_month" name="date[month]" class="my-month">\n).dup
     expected << %(<option value="1">January</option>\n<option value="2">February</option>\n<option value="3">March</option>\n<option value="4">April</option>\n<option value="5">May</option>\n<option value="6">June</option>\n<option value="7">July</option>\n<option value="8" selected="selected">August</option>\n<option value="9">September</option>\n<option value="10">October</option>\n<option value="11">November</option>\n<option value="12">December</option>\n)
     expected << "</select>\n"
 
@@ -459,7 +459,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_year
-    expected = %(<select id="date_year" name="date[year]">\n)
+    expected = %(<select id="date_year" name="date[year]">\n).dup
     expected << %(<option value="2003" selected="selected">2003</option>\n<option value="2004">2004</option>\n<option value="2005">2005</option>\n)
     expected << "</select>\n"
 
@@ -468,7 +468,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_year_with_disabled
-    expected = %(<select id="date_year" name="date[year]" disabled="disabled">\n)
+    expected = %(<select id="date_year" name="date[year]" disabled="disabled">\n).dup
     expected << %(<option value="2003" selected="selected">2003</option>\n<option value="2004">2004</option>\n<option value="2005">2005</option>\n)
     expected << "</select>\n"
 
@@ -477,7 +477,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_year_with_field_name_override
-    expected = %(<select id="date_annee" name="date[annee]">\n)
+    expected = %(<select id="date_annee" name="date[annee]">\n).dup
     expected << %(<option value="2003" selected="selected">2003</option>\n<option value="2004">2004</option>\n<option value="2005">2005</option>\n)
     expected << "</select>\n"
 
@@ -486,7 +486,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_year_with_type_discarding
-    expected = %(<select id="date_year" name="date_year">\n)
+    expected = %(<select id="date_year" name="date_year">\n).dup
     expected << %(<option value="2003" selected="selected">2003</option>\n<option value="2004">2004</option>\n<option value="2005">2005</option>\n)
     expected << "</select>\n"
 
@@ -497,7 +497,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_year_descending
-    expected = %(<select id="date_year" name="date[year]">\n)
+    expected = %(<select id="date_year" name="date[year]">\n).dup
     expected << %(<option value="2005" selected="selected">2005</option>\n<option value="2004">2004</option>\n<option value="2003">2003</option>\n)
     expected << "</select>\n"
 
@@ -514,7 +514,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_year_with_html_options
-    expected = %(<select id="date_year" name="date[year]" class="selector" accesskey="M">\n)
+    expected = %(<select id="date_year" name="date[year]" class="selector" accesskey="M">\n).dup
     expected << %(<option value="2003" selected="selected">2003</option>\n<option value="2004">2004</option>\n<option value="2005">2005</option>\n)
     expected << "</select>\n"
 
@@ -522,7 +522,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_year_with_default_prompt
-    expected = %(<select id="date_year" name="date[year]">\n)
+    expected = %(<select id="date_year" name="date[year]">\n).dup
     expected << %(<option value="">Year</option>\n<option value="2003">2003</option>\n<option value="2004">2004</option>\n<option value="2005">2005</option>\n)
     expected << "</select>\n"
 
@@ -530,7 +530,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_year_with_custom_prompt
-    expected = %(<select id="date_year" name="date[year]">\n)
+    expected = %(<select id="date_year" name="date[year]">\n).dup
     expected << %(<option value="">Choose year</option>\n<option value="2003">2003</option>\n<option value="2004">2004</option>\n<option value="2005">2005</option>\n)
     expected << "</select>\n"
 
@@ -538,7 +538,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_year_with_generic_with_css_classes
-    expected = %(<select id="date_year" name="date[year]" class="year">\n)
+    expected = %(<select id="date_year" name="date[year]" class="year">\n).dup
     expected << %(<option value="2003">2003</option>\n<option value="2004">2004</option>\n<option value="2005">2005</option>\n)
     expected << "</select>\n"
 
@@ -546,7 +546,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_year_with_custom_with_css_classes
-    expected = %(<select id="date_year" name="date[year]" class="my-year">\n)
+    expected = %(<select id="date_year" name="date[year]" class="my-year">\n).dup
     expected << %(<option value="2003">2003</option>\n<option value="2004">2004</option>\n<option value="2005">2005</option>\n)
     expected << "</select>\n"
 
@@ -554,14 +554,14 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_year_with_position
-    expected = %(<select id="date_year_1i" name="date[year(1i)]">\n)
+    expected = %(<select id="date_year_1i" name="date[year(1i)]">\n).dup
     expected << %(<option value="2003">2003</option>\n<option value="2004">2004</option>\n<option value="2005">2005</option>\n)
     expected << "</select>\n"
     assert_dom_equal expected, select_year(Date.current, include_position: true,  start_year: 2003, end_year: 2005)
   end
 
   def test_select_hour
-    expected = %(<select id="date_hour" name="date[hour]">\n)
+    expected = %(<select id="date_hour" name="date[hour]">\n).dup
     expected << %(<option value="00">00</option>\n<option value="01">01</option>\n<option value="02">02</option>\n<option value="03">03</option>\n<option value="04">04</option>\n<option value="05">05</option>\n<option value="06">06</option>\n<option value="07">07</option>\n<option value="08" selected="selected">08</option>\n<option value="09">09</option>\n<option value="10">10</option>\n<option value="11">11</option>\n<option value="12">12</option>\n<option value="13">13</option>\n<option value="14">14</option>\n<option value="15">15</option>\n<option value="16">16</option>\n<option value="17">17</option>\n<option value="18">18</option>\n<option value="19">19</option>\n<option value="20">20</option>\n<option value="21">21</option>\n<option value="22">22</option>\n<option value="23">23</option>\n)
     expected << "</select>\n"
 
@@ -569,7 +569,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_hour_with_ampm
-    expected = %(<select id="date_hour" name="date[hour]">\n)
+    expected = %(<select id="date_hour" name="date[hour]">\n).dup
     expected << %(<option value="00">12 AM</option>\n<option value="01">01 AM</option>\n<option value="02">02 AM</option>\n<option value="03">03 AM</option>\n<option value="04">04 AM</option>\n<option value="05">05 AM</option>\n<option value="06">06 AM</option>\n<option value="07">07 AM</option>\n<option value="08" selected="selected">08 AM</option>\n<option value="09">09 AM</option>\n<option value="10">10 AM</option>\n<option value="11">11 AM</option>\n<option value="12">12 PM</option>\n<option value="13">01 PM</option>\n<option value="14">02 PM</option>\n<option value="15">03 PM</option>\n<option value="16">04 PM</option>\n<option value="17">05 PM</option>\n<option value="18">06 PM</option>\n<option value="19">07 PM</option>\n<option value="20">08 PM</option>\n<option value="21">09 PM</option>\n<option value="22">10 PM</option>\n<option value="23">11 PM</option>\n)
     expected << "</select>\n"
 
@@ -577,7 +577,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_hour_with_disabled
-    expected = %(<select id="date_hour" name="date[hour]" disabled="disabled">\n)
+    expected = %(<select id="date_hour" name="date[hour]" disabled="disabled">\n).dup
     expected << %(<option value="00">00</option>\n<option value="01">01</option>\n<option value="02">02</option>\n<option value="03">03</option>\n<option value="04">04</option>\n<option value="05">05</option>\n<option value="06">06</option>\n<option value="07">07</option>\n<option value="08" selected="selected">08</option>\n<option value="09">09</option>\n<option value="10">10</option>\n<option value="11">11</option>\n<option value="12">12</option>\n<option value="13">13</option>\n<option value="14">14</option>\n<option value="15">15</option>\n<option value="16">16</option>\n<option value="17">17</option>\n<option value="18">18</option>\n<option value="19">19</option>\n<option value="20">20</option>\n<option value="21">21</option>\n<option value="22">22</option>\n<option value="23">23</option>\n)
     expected << "</select>\n"
 
@@ -585,7 +585,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_hour_with_field_name_override
-    expected = %(<select id="date_heure" name="date[heure]">\n)
+    expected = %(<select id="date_heure" name="date[heure]">\n).dup
     expected << %(<option value="00">00</option>\n<option value="01">01</option>\n<option value="02">02</option>\n<option value="03">03</option>\n<option value="04">04</option>\n<option value="05">05</option>\n<option value="06">06</option>\n<option value="07">07</option>\n<option value="08" selected="selected">08</option>\n<option value="09">09</option>\n<option value="10">10</option>\n<option value="11">11</option>\n<option value="12">12</option>\n<option value="13">13</option>\n<option value="14">14</option>\n<option value="15">15</option>\n<option value="16">16</option>\n<option value="17">17</option>\n<option value="18">18</option>\n<option value="19">19</option>\n<option value="20">20</option>\n<option value="21">21</option>\n<option value="22">22</option>\n<option value="23">23</option>\n)
     expected << "</select>\n"
 
@@ -593,7 +593,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_hour_with_blank
-    expected = %(<select id="date_hour" name="date[hour]">\n)
+    expected = %(<select id="date_hour" name="date[hour]">\n).dup
     expected << %(<option value=""></option>\n<option value="00">00</option>\n<option value="01">01</option>\n<option value="02">02</option>\n<option value="03">03</option>\n<option value="04">04</option>\n<option value="05">05</option>\n<option value="06">06</option>\n<option value="07">07</option>\n<option value="08" selected="selected">08</option>\n<option value="09">09</option>\n<option value="10">10</option>\n<option value="11">11</option>\n<option value="12">12</option>\n<option value="13">13</option>\n<option value="14">14</option>\n<option value="15">15</option>\n<option value="16">16</option>\n<option value="17">17</option>\n<option value="18">18</option>\n<option value="19">19</option>\n<option value="20">20</option>\n<option value="21">21</option>\n<option value="22">22</option>\n<option value="23">23</option>\n)
     expected << "</select>\n"
 
@@ -601,7 +601,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_hour_nil_with_blank
-    expected = %(<select id="date_hour" name="date[hour]">\n)
+    expected = %(<select id="date_hour" name="date[hour]">\n).dup
     expected << %(<option value=""></option>\n<option value="00">00</option>\n<option value="01">01</option>\n<option value="02">02</option>\n<option value="03">03</option>\n<option value="04">04</option>\n<option value="05">05</option>\n<option value="06">06</option>\n<option value="07">07</option>\n<option value="08">08</option>\n<option value="09">09</option>\n<option value="10">10</option>\n<option value="11">11</option>\n<option value="12">12</option>\n<option value="13">13</option>\n<option value="14">14</option>\n<option value="15">15</option>\n<option value="16">16</option>\n<option value="17">17</option>\n<option value="18">18</option>\n<option value="19">19</option>\n<option value="20">20</option>\n<option value="21">21</option>\n<option value="22">22</option>\n<option value="23">23</option>\n)
     expected << "</select>\n"
 
@@ -609,7 +609,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_hour_with_html_options
-    expected = %(<select id="date_hour" name="date[hour]" class="selector" accesskey="M">\n)
+    expected = %(<select id="date_hour" name="date[hour]" class="selector" accesskey="M">\n).dup
     expected << %(<option value="00">00</option>\n<option value="01">01</option>\n<option value="02">02</option>\n<option value="03">03</option>\n<option value="04">04</option>\n<option value="05">05</option>\n<option value="06">06</option>\n<option value="07">07</option>\n<option value="08" selected="selected">08</option>\n<option value="09">09</option>\n<option value="10">10</option>\n<option value="11">11</option>\n<option value="12">12</option>\n<option value="13">13</option>\n<option value="14">14</option>\n<option value="15">15</option>\n<option value="16">16</option>\n<option value="17">17</option>\n<option value="18">18</option>\n<option value="19">19</option>\n<option value="20">20</option>\n<option value="21">21</option>\n<option value="22">22</option>\n<option value="23">23</option>\n)
     expected << "</select>\n"
 
@@ -617,7 +617,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_hour_with_default_prompt
-    expected = %(<select id="date_hour" name="date[hour]">\n)
+    expected = %(<select id="date_hour" name="date[hour]">\n).dup
     expected << %(<option value="">Hour</option>\n<option value="00">00</option>\n<option value="01">01</option>\n<option value="02">02</option>\n<option value="03">03</option>\n<option value="04">04</option>\n<option value="05">05</option>\n<option value="06">06</option>\n<option value="07">07</option>\n<option value="08" selected="selected">08</option>\n<option value="09">09</option>\n<option value="10">10</option>\n<option value="11">11</option>\n<option value="12">12</option>\n<option value="13">13</option>\n<option value="14">14</option>\n<option value="15">15</option>\n<option value="16">16</option>\n<option value="17">17</option>\n<option value="18">18</option>\n<option value="19">19</option>\n<option value="20">20</option>\n<option value="21">21</option>\n<option value="22">22</option>\n<option value="23">23</option>\n)
     expected << "</select>\n"
 
@@ -625,7 +625,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_hour_with_custom_prompt
-    expected = %(<select id="date_hour" name="date[hour]">\n)
+    expected = %(<select id="date_hour" name="date[hour]">\n).dup
     expected << %(<option value="">Choose hour</option>\n<option value="00">00</option>\n<option value="01">01</option>\n<option value="02">02</option>\n<option value="03">03</option>\n<option value="04">04</option>\n<option value="05">05</option>\n<option value="06">06</option>\n<option value="07">07</option>\n<option value="08" selected="selected">08</option>\n<option value="09">09</option>\n<option value="10">10</option>\n<option value="11">11</option>\n<option value="12">12</option>\n<option value="13">13</option>\n<option value="14">14</option>\n<option value="15">15</option>\n<option value="16">16</option>\n<option value="17">17</option>\n<option value="18">18</option>\n<option value="19">19</option>\n<option value="20">20</option>\n<option value="21">21</option>\n<option value="22">22</option>\n<option value="23">23</option>\n)
     expected << "</select>\n"
 
@@ -633,7 +633,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_hour_with_generic_with_css_classes
-    expected = %(<select id="date_hour" name="date[hour]" class="hour">\n)
+    expected = %(<select id="date_hour" name="date[hour]" class="hour">\n).dup
     expected << %(<option value="00">00</option>\n<option value="01">01</option>\n<option value="02">02</option>\n<option value="03">03</option>\n<option value="04">04</option>\n<option value="05">05</option>\n<option value="06">06</option>\n<option value="07">07</option>\n<option value="08" selected="selected">08</option>\n<option value="09">09</option>\n<option value="10">10</option>\n<option value="11">11</option>\n<option value="12">12</option>\n<option value="13">13</option>\n<option value="14">14</option>\n<option value="15">15</option>\n<option value="16">16</option>\n<option value="17">17</option>\n<option value="18">18</option>\n<option value="19">19</option>\n<option value="20">20</option>\n<option value="21">21</option>\n<option value="22">22</option>\n<option value="23">23</option>\n)
     expected << "</select>\n"
 
@@ -641,7 +641,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_hour_with_custom_with_css_classes
-    expected = %(<select id="date_hour" name="date[hour]" class="my-hour">\n)
+    expected = %(<select id="date_hour" name="date[hour]" class="my-hour">\n).dup
     expected << %(<option value="00">00</option>\n<option value="01">01</option>\n<option value="02">02</option>\n<option value="03">03</option>\n<option value="04">04</option>\n<option value="05">05</option>\n<option value="06">06</option>\n<option value="07">07</option>\n<option value="08" selected="selected">08</option>\n<option value="09">09</option>\n<option value="10">10</option>\n<option value="11">11</option>\n<option value="12">12</option>\n<option value="13">13</option>\n<option value="14">14</option>\n<option value="15">15</option>\n<option value="16">16</option>\n<option value="17">17</option>\n<option value="18">18</option>\n<option value="19">19</option>\n<option value="20">20</option>\n<option value="21">21</option>\n<option value="22">22</option>\n<option value="23">23</option>\n)
     expected << "</select>\n"
 
@@ -649,7 +649,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_minute
-    expected = %(<select id="date_minute" name="date[minute]">\n)
+    expected = %(<select id="date_minute" name="date[minute]">\n).dup
     expected << %(<option value="00">00</option>\n<option value="01">01</option>\n<option value="02">02</option>\n<option value="03">03</option>\n<option value="04" selected="selected">04</option>\n<option value="05">05</option>\n<option value="06">06</option>\n<option value="07">07</option>\n<option value="08">08</option>\n<option value="09">09</option>\n<option value="10">10</option>\n<option value="11">11</option>\n<option value="12">12</option>\n<option value="13">13</option>\n<option value="14">14</option>\n<option value="15">15</option>\n<option value="16">16</option>\n<option value="17">17</option>\n<option value="18">18</option>\n<option value="19">19</option>\n<option value="20">20</option>\n<option value="21">21</option>\n<option value="22">22</option>\n<option value="23">23</option>\n<option value="24">24</option>\n<option value="25">25</option>\n<option value="26">26</option>\n<option value="27">27</option>\n<option value="28">28</option>\n<option value="29">29</option>\n<option value="30">30</option>\n<option value="31">31</option>\n<option value="32">32</option>\n<option value="33">33</option>\n<option value="34">34</option>\n<option value="35">35</option>\n<option value="36">36</option>\n<option value="37">37</option>\n<option value="38">38</option>\n<option value="39">39</option>\n<option value="40">40</option>\n<option value="41">41</option>\n<option value="42">42</option>\n<option value="43">43</option>\n<option value="44">44</option>\n<option value="45">45</option>\n<option value="46">46</option>\n<option value="47">47</option>\n<option value="48">48</option>\n<option value="49">49</option>\n<option value="50">50</option>\n<option value="51">51</option>\n<option value="52">52</option>\n<option value="53">53</option>\n<option value="54">54</option>\n<option value="55">55</option>\n<option value="56">56</option>\n<option value="57">57</option>\n<option value="58">58</option>\n<option value="59">59</option>\n)
     expected << "</select>\n"
 
@@ -657,7 +657,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_minute_with_disabled
-    expected = %(<select id="date_minute" name="date[minute]" disabled="disabled">\n)
+    expected = %(<select id="date_minute" name="date[minute]" disabled="disabled">\n).dup
     expected << %(<option value="00">00</option>\n<option value="01">01</option>\n<option value="02">02</option>\n<option value="03">03</option>\n<option value="04" selected="selected">04</option>\n<option value="05">05</option>\n<option value="06">06</option>\n<option value="07">07</option>\n<option value="08">08</option>\n<option value="09">09</option>\n<option value="10">10</option>\n<option value="11">11</option>\n<option value="12">12</option>\n<option value="13">13</option>\n<option value="14">14</option>\n<option value="15">15</option>\n<option value="16">16</option>\n<option value="17">17</option>\n<option value="18">18</option>\n<option value="19">19</option>\n<option value="20">20</option>\n<option value="21">21</option>\n<option value="22">22</option>\n<option value="23">23</option>\n<option value="24">24</option>\n<option value="25">25</option>\n<option value="26">26</option>\n<option value="27">27</option>\n<option value="28">28</option>\n<option value="29">29</option>\n<option value="30">30</option>\n<option value="31">31</option>\n<option value="32">32</option>\n<option value="33">33</option>\n<option value="34">34</option>\n<option value="35">35</option>\n<option value="36">36</option>\n<option value="37">37</option>\n<option value="38">38</option>\n<option value="39">39</option>\n<option value="40">40</option>\n<option value="41">41</option>\n<option value="42">42</option>\n<option value="43">43</option>\n<option value="44">44</option>\n<option value="45">45</option>\n<option value="46">46</option>\n<option value="47">47</option>\n<option value="48">48</option>\n<option value="49">49</option>\n<option value="50">50</option>\n<option value="51">51</option>\n<option value="52">52</option>\n<option value="53">53</option>\n<option value="54">54</option>\n<option value="55">55</option>\n<option value="56">56</option>\n<option value="57">57</option>\n<option value="58">58</option>\n<option value="59">59</option>\n)
     expected << "</select>\n"
 
@@ -665,7 +665,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_minute_with_field_name_override
-    expected = %(<select id="date_minuto" name="date[minuto]">\n)
+    expected = %(<select id="date_minuto" name="date[minuto]">\n).dup
     expected << %(<option value="00">00</option>\n<option value="01">01</option>\n<option value="02">02</option>\n<option value="03">03</option>\n<option value="04" selected="selected">04</option>\n<option value="05">05</option>\n<option value="06">06</option>\n<option value="07">07</option>\n<option value="08">08</option>\n<option value="09">09</option>\n<option value="10">10</option>\n<option value="11">11</option>\n<option value="12">12</option>\n<option value="13">13</option>\n<option value="14">14</option>\n<option value="15">15</option>\n<option value="16">16</option>\n<option value="17">17</option>\n<option value="18">18</option>\n<option value="19">19</option>\n<option value="20">20</option>\n<option value="21">21</option>\n<option value="22">22</option>\n<option value="23">23</option>\n<option value="24">24</option>\n<option value="25">25</option>\n<option value="26">26</option>\n<option value="27">27</option>\n<option value="28">28</option>\n<option value="29">29</option>\n<option value="30">30</option>\n<option value="31">31</option>\n<option value="32">32</option>\n<option value="33">33</option>\n<option value="34">34</option>\n<option value="35">35</option>\n<option value="36">36</option>\n<option value="37">37</option>\n<option value="38">38</option>\n<option value="39">39</option>\n<option value="40">40</option>\n<option value="41">41</option>\n<option value="42">42</option>\n<option value="43">43</option>\n<option value="44">44</option>\n<option value="45">45</option>\n<option value="46">46</option>\n<option value="47">47</option>\n<option value="48">48</option>\n<option value="49">49</option>\n<option value="50">50</option>\n<option value="51">51</option>\n<option value="52">52</option>\n<option value="53">53</option>\n<option value="54">54</option>\n<option value="55">55</option>\n<option value="56">56</option>\n<option value="57">57</option>\n<option value="58">58</option>\n<option value="59">59</option>\n)
     expected << "</select>\n"
 
@@ -673,7 +673,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_minute_with_blank
-    expected = %(<select id="date_minute" name="date[minute]">\n)
+    expected = %(<select id="date_minute" name="date[minute]">\n).dup
     expected << %(<option value=""></option>\n<option value="00">00</option>\n<option value="01">01</option>\n<option value="02">02</option>\n<option value="03">03</option>\n<option value="04" selected="selected">04</option>\n<option value="05">05</option>\n<option value="06">06</option>\n<option value="07">07</option>\n<option value="08">08</option>\n<option value="09">09</option>\n<option value="10">10</option>\n<option value="11">11</option>\n<option value="12">12</option>\n<option value="13">13</option>\n<option value="14">14</option>\n<option value="15">15</option>\n<option value="16">16</option>\n<option value="17">17</option>\n<option value="18">18</option>\n<option value="19">19</option>\n<option value="20">20</option>\n<option value="21">21</option>\n<option value="22">22</option>\n<option value="23">23</option>\n<option value="24">24</option>\n<option value="25">25</option>\n<option value="26">26</option>\n<option value="27">27</option>\n<option value="28">28</option>\n<option value="29">29</option>\n<option value="30">30</option>\n<option value="31">31</option>\n<option value="32">32</option>\n<option value="33">33</option>\n<option value="34">34</option>\n<option value="35">35</option>\n<option value="36">36</option>\n<option value="37">37</option>\n<option value="38">38</option>\n<option value="39">39</option>\n<option value="40">40</option>\n<option value="41">41</option>\n<option value="42">42</option>\n<option value="43">43</option>\n<option value="44">44</option>\n<option value="45">45</option>\n<option value="46">46</option>\n<option value="47">47</option>\n<option value="48">48</option>\n<option value="49">49</option>\n<option value="50">50</option>\n<option value="51">51</option>\n<option value="52">52</option>\n<option value="53">53</option>\n<option value="54">54</option>\n<option value="55">55</option>\n<option value="56">56</option>\n<option value="57">57</option>\n<option value="58">58</option>\n<option value="59">59</option>\n)
     expected << "</select>\n"
 
@@ -681,7 +681,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_minute_with_blank_and_step
-    expected = %(<select id="date_minute" name="date[minute]">\n)
+    expected = %(<select id="date_minute" name="date[minute]">\n).dup
     expected << %(<option value=""></option>\n<option value="00">00</option>\n<option value="15">15</option>\n<option value="30">30</option>\n<option value="45">45</option>\n)
     expected << "</select>\n"
 
@@ -689,7 +689,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_minute_nil_with_blank
-    expected = %(<select id="date_minute" name="date[minute]">\n)
+    expected = %(<select id="date_minute" name="date[minute]">\n).dup
     expected << %(<option value=""></option>\n<option value="00">00</option>\n<option value="01">01</option>\n<option value="02">02</option>\n<option value="03">03</option>\n<option value="04">04</option>\n<option value="05">05</option>\n<option value="06">06</option>\n<option value="07">07</option>\n<option value="08">08</option>\n<option value="09">09</option>\n<option value="10">10</option>\n<option value="11">11</option>\n<option value="12">12</option>\n<option value="13">13</option>\n<option value="14">14</option>\n<option value="15">15</option>\n<option value="16">16</option>\n<option value="17">17</option>\n<option value="18">18</option>\n<option value="19">19</option>\n<option value="20">20</option>\n<option value="21">21</option>\n<option value="22">22</option>\n<option value="23">23</option>\n<option value="24">24</option>\n<option value="25">25</option>\n<option value="26">26</option>\n<option value="27">27</option>\n<option value="28">28</option>\n<option value="29">29</option>\n<option value="30">30</option>\n<option value="31">31</option>\n<option value="32">32</option>\n<option value="33">33</option>\n<option value="34">34</option>\n<option value="35">35</option>\n<option value="36">36</option>\n<option value="37">37</option>\n<option value="38">38</option>\n<option value="39">39</option>\n<option value="40">40</option>\n<option value="41">41</option>\n<option value="42">42</option>\n<option value="43">43</option>\n<option value="44">44</option>\n<option value="45">45</option>\n<option value="46">46</option>\n<option value="47">47</option>\n<option value="48">48</option>\n<option value="49">49</option>\n<option value="50">50</option>\n<option value="51">51</option>\n<option value="52">52</option>\n<option value="53">53</option>\n<option value="54">54</option>\n<option value="55">55</option>\n<option value="56">56</option>\n<option value="57">57</option>\n<option value="58">58</option>\n<option value="59">59</option>\n)
     expected << "</select>\n"
 
@@ -697,7 +697,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_minute_nil_with_blank_and_step
-    expected = %(<select id="date_minute" name="date[minute]">\n)
+    expected = %(<select id="date_minute" name="date[minute]">\n).dup
     expected << %(<option value=""></option>\n<option value="00">00</option>\n<option value="15">15</option>\n<option value="30">30</option>\n<option value="45">45</option>\n)
     expected << "</select>\n"
 
@@ -713,7 +713,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_minute_with_html_options
-    expected = %(<select id="date_minute" name="date[minute]" class="selector" accesskey="M">\n)
+    expected = %(<select id="date_minute" name="date[minute]" class="selector" accesskey="M">\n).dup
     expected << %(<option value="00">00</option>\n<option value="01">01</option>\n<option value="02">02</option>\n<option value="03">03</option>\n<option value="04" selected="selected">04</option>\n<option value="05">05</option>\n<option value="06">06</option>\n<option value="07">07</option>\n<option value="08">08</option>\n<option value="09">09</option>\n<option value="10">10</option>\n<option value="11">11</option>\n<option value="12">12</option>\n<option value="13">13</option>\n<option value="14">14</option>\n<option value="15">15</option>\n<option value="16">16</option>\n<option value="17">17</option>\n<option value="18">18</option>\n<option value="19">19</option>\n<option value="20">20</option>\n<option value="21">21</option>\n<option value="22">22</option>\n<option value="23">23</option>\n<option value="24">24</option>\n<option value="25">25</option>\n<option value="26">26</option>\n<option value="27">27</option>\n<option value="28">28</option>\n<option value="29">29</option>\n<option value="30">30</option>\n<option value="31">31</option>\n<option value="32">32</option>\n<option value="33">33</option>\n<option value="34">34</option>\n<option value="35">35</option>\n<option value="36">36</option>\n<option value="37">37</option>\n<option value="38">38</option>\n<option value="39">39</option>\n<option value="40">40</option>\n<option value="41">41</option>\n<option value="42">42</option>\n<option value="43">43</option>\n<option value="44">44</option>\n<option value="45">45</option>\n<option value="46">46</option>\n<option value="47">47</option>\n<option value="48">48</option>\n<option value="49">49</option>\n<option value="50">50</option>\n<option value="51">51</option>\n<option value="52">52</option>\n<option value="53">53</option>\n<option value="54">54</option>\n<option value="55">55</option>\n<option value="56">56</option>\n<option value="57">57</option>\n<option value="58">58</option>\n<option value="59">59</option>\n)
     expected << "</select>\n"
 
@@ -721,7 +721,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_minute_with_default_prompt
-    expected = %(<select id="date_minute" name="date[minute]">\n)
+    expected = %(<select id="date_minute" name="date[minute]">\n).dup
     expected << %(<option value="">Minute</option>\n<option value="00">00</option>\n<option value="01">01</option>\n<option value="02">02</option>\n<option value="03">03</option>\n<option value="04" selected="selected">04</option>\n<option value="05">05</option>\n<option value="06">06</option>\n<option value="07">07</option>\n<option value="08">08</option>\n<option value="09">09</option>\n<option value="10">10</option>\n<option value="11">11</option>\n<option value="12">12</option>\n<option value="13">13</option>\n<option value="14">14</option>\n<option value="15">15</option>\n<option value="16">16</option>\n<option value="17">17</option>\n<option value="18">18</option>\n<option value="19">19</option>\n<option value="20">20</option>\n<option value="21">21</option>\n<option value="22">22</option>\n<option value="23">23</option>\n<option value="24">24</option>\n<option value="25">25</option>\n<option value="26">26</option>\n<option value="27">27</option>\n<option value="28">28</option>\n<option value="29">29</option>\n<option value="30">30</option>\n<option value="31">31</option>\n<option value="32">32</option>\n<option value="33">33</option>\n<option value="34">34</option>\n<option value="35">35</option>\n<option value="36">36</option>\n<option value="37">37</option>\n<option value="38">38</option>\n<option value="39">39</option>\n<option value="40">40</option>\n<option value="41">41</option>\n<option value="42">42</option>\n<option value="43">43</option>\n<option value="44">44</option>\n<option value="45">45</option>\n<option value="46">46</option>\n<option value="47">47</option>\n<option value="48">48</option>\n<option value="49">49</option>\n<option value="50">50</option>\n<option value="51">51</option>\n<option value="52">52</option>\n<option value="53">53</option>\n<option value="54">54</option>\n<option value="55">55</option>\n<option value="56">56</option>\n<option value="57">57</option>\n<option value="58">58</option>\n<option value="59">59</option>\n)
     expected << "</select>\n"
 
@@ -729,7 +729,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_minute_with_custom_prompt
-    expected = %(<select id="date_minute" name="date[minute]">\n)
+    expected = %(<select id="date_minute" name="date[minute]">\n).dup
     expected << %(<option value="">Choose minute</option>\n<option value="00">00</option>\n<option value="01">01</option>\n<option value="02">02</option>\n<option value="03">03</option>\n<option value="04" selected="selected">04</option>\n<option value="05">05</option>\n<option value="06">06</option>\n<option value="07">07</option>\n<option value="08">08</option>\n<option value="09">09</option>\n<option value="10">10</option>\n<option value="11">11</option>\n<option value="12">12</option>\n<option value="13">13</option>\n<option value="14">14</option>\n<option value="15">15</option>\n<option value="16">16</option>\n<option value="17">17</option>\n<option value="18">18</option>\n<option value="19">19</option>\n<option value="20">20</option>\n<option value="21">21</option>\n<option value="22">22</option>\n<option value="23">23</option>\n<option value="24">24</option>\n<option value="25">25</option>\n<option value="26">26</option>\n<option value="27">27</option>\n<option value="28">28</option>\n<option value="29">29</option>\n<option value="30">30</option>\n<option value="31">31</option>\n<option value="32">32</option>\n<option value="33">33</option>\n<option value="34">34</option>\n<option value="35">35</option>\n<option value="36">36</option>\n<option value="37">37</option>\n<option value="38">38</option>\n<option value="39">39</option>\n<option value="40">40</option>\n<option value="41">41</option>\n<option value="42">42</option>\n<option value="43">43</option>\n<option value="44">44</option>\n<option value="45">45</option>\n<option value="46">46</option>\n<option value="47">47</option>\n<option value="48">48</option>\n<option value="49">49</option>\n<option value="50">50</option>\n<option value="51">51</option>\n<option value="52">52</option>\n<option value="53">53</option>\n<option value="54">54</option>\n<option value="55">55</option>\n<option value="56">56</option>\n<option value="57">57</option>\n<option value="58">58</option>\n<option value="59">59</option>\n)
     expected << "</select>\n"
 
@@ -737,7 +737,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_minute_with_generic_with_css_classes
-    expected = %(<select id="date_minute" name="date[minute]" class="minute">\n)
+    expected = %(<select id="date_minute" name="date[minute]" class="minute">\n).dup
     expected << %(<option value="00">00</option>\n<option value="01">01</option>\n<option value="02">02</option>\n<option value="03">03</option>\n<option value="04" selected="selected">04</option>\n<option value="05">05</option>\n<option value="06">06</option>\n<option value="07">07</option>\n<option value="08">08</option>\n<option value="09">09</option>\n<option value="10">10</option>\n<option value="11">11</option>\n<option value="12">12</option>\n<option value="13">13</option>\n<option value="14">14</option>\n<option value="15">15</option>\n<option value="16">16</option>\n<option value="17">17</option>\n<option value="18">18</option>\n<option value="19">19</option>\n<option value="20">20</option>\n<option value="21">21</option>\n<option value="22">22</option>\n<option value="23">23</option>\n<option value="24">24</option>\n<option value="25">25</option>\n<option value="26">26</option>\n<option value="27">27</option>\n<option value="28">28</option>\n<option value="29">29</option>\n<option value="30">30</option>\n<option value="31">31</option>\n<option value="32">32</option>\n<option value="33">33</option>\n<option value="34">34</option>\n<option value="35">35</option>\n<option value="36">36</option>\n<option value="37">37</option>\n<option value="38">38</option>\n<option value="39">39</option>\n<option value="40">40</option>\n<option value="41">41</option>\n<option value="42">42</option>\n<option value="43">43</option>\n<option value="44">44</option>\n<option value="45">45</option>\n<option value="46">46</option>\n<option value="47">47</option>\n<option value="48">48</option>\n<option value="49">49</option>\n<option value="50">50</option>\n<option value="51">51</option>\n<option value="52">52</option>\n<option value="53">53</option>\n<option value="54">54</option>\n<option value="55">55</option>\n<option value="56">56</option>\n<option value="57">57</option>\n<option value="58">58</option>\n<option value="59">59</option>\n)
     expected << "</select>\n"
 
@@ -745,7 +745,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_minute_with_custom_with_css_classes
-    expected = %(<select id="date_minute" name="date[minute]" class="my-minute">\n)
+    expected = %(<select id="date_minute" name="date[minute]" class="my-minute">\n).dup
     expected << %(<option value="00">00</option>\n<option value="01">01</option>\n<option value="02">02</option>\n<option value="03">03</option>\n<option value="04" selected="selected">04</option>\n<option value="05">05</option>\n<option value="06">06</option>\n<option value="07">07</option>\n<option value="08">08</option>\n<option value="09">09</option>\n<option value="10">10</option>\n<option value="11">11</option>\n<option value="12">12</option>\n<option value="13">13</option>\n<option value="14">14</option>\n<option value="15">15</option>\n<option value="16">16</option>\n<option value="17">17</option>\n<option value="18">18</option>\n<option value="19">19</option>\n<option value="20">20</option>\n<option value="21">21</option>\n<option value="22">22</option>\n<option value="23">23</option>\n<option value="24">24</option>\n<option value="25">25</option>\n<option value="26">26</option>\n<option value="27">27</option>\n<option value="28">28</option>\n<option value="29">29</option>\n<option value="30">30</option>\n<option value="31">31</option>\n<option value="32">32</option>\n<option value="33">33</option>\n<option value="34">34</option>\n<option value="35">35</option>\n<option value="36">36</option>\n<option value="37">37</option>\n<option value="38">38</option>\n<option value="39">39</option>\n<option value="40">40</option>\n<option value="41">41</option>\n<option value="42">42</option>\n<option value="43">43</option>\n<option value="44">44</option>\n<option value="45">45</option>\n<option value="46">46</option>\n<option value="47">47</option>\n<option value="48">48</option>\n<option value="49">49</option>\n<option value="50">50</option>\n<option value="51">51</option>\n<option value="52">52</option>\n<option value="53">53</option>\n<option value="54">54</option>\n<option value="55">55</option>\n<option value="56">56</option>\n<option value="57">57</option>\n<option value="58">58</option>\n<option value="59">59</option>\n)
     expected << "</select>\n"
 
@@ -753,7 +753,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_second
-    expected = %(<select id="date_second" name="date[second]">\n)
+    expected = %(<select id="date_second" name="date[second]">\n).dup
     expected << %(<option value="00">00</option>\n<option value="01">01</option>\n<option value="02">02</option>\n<option value="03">03</option>\n<option value="04">04</option>\n<option value="05">05</option>\n<option value="06">06</option>\n<option value="07">07</option>\n<option value="08">08</option>\n<option value="09">09</option>\n<option value="10">10</option>\n<option value="11">11</option>\n<option value="12">12</option>\n<option value="13">13</option>\n<option value="14">14</option>\n<option value="15">15</option>\n<option value="16">16</option>\n<option value="17">17</option>\n<option value="18" selected="selected">18</option>\n<option value="19">19</option>\n<option value="20">20</option>\n<option value="21">21</option>\n<option value="22">22</option>\n<option value="23">23</option>\n<option value="24">24</option>\n<option value="25">25</option>\n<option value="26">26</option>\n<option value="27">27</option>\n<option value="28">28</option>\n<option value="29">29</option>\n<option value="30">30</option>\n<option value="31">31</option>\n<option value="32">32</option>\n<option value="33">33</option>\n<option value="34">34</option>\n<option value="35">35</option>\n<option value="36">36</option>\n<option value="37">37</option>\n<option value="38">38</option>\n<option value="39">39</option>\n<option value="40">40</option>\n<option value="41">41</option>\n<option value="42">42</option>\n<option value="43">43</option>\n<option value="44">44</option>\n<option value="45">45</option>\n<option value="46">46</option>\n<option value="47">47</option>\n<option value="48">48</option>\n<option value="49">49</option>\n<option value="50">50</option>\n<option value="51">51</option>\n<option value="52">52</option>\n<option value="53">53</option>\n<option value="54">54</option>\n<option value="55">55</option>\n<option value="56">56</option>\n<option value="57">57</option>\n<option value="58">58</option>\n<option value="59">59</option>\n)
     expected << "</select>\n"
 
@@ -761,7 +761,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_second_with_disabled
-    expected = %(<select id="date_second" name="date[second]" disabled="disabled">\n)
+    expected = %(<select id="date_second" name="date[second]" disabled="disabled">\n).dup
     expected << %(<option value="00">00</option>\n<option value="01">01</option>\n<option value="02">02</option>\n<option value="03">03</option>\n<option value="04">04</option>\n<option value="05">05</option>\n<option value="06">06</option>\n<option value="07">07</option>\n<option value="08">08</option>\n<option value="09">09</option>\n<option value="10">10</option>\n<option value="11">11</option>\n<option value="12">12</option>\n<option value="13">13</option>\n<option value="14">14</option>\n<option value="15">15</option>\n<option value="16">16</option>\n<option value="17">17</option>\n<option value="18" selected="selected">18</option>\n<option value="19">19</option>\n<option value="20">20</option>\n<option value="21">21</option>\n<option value="22">22</option>\n<option value="23">23</option>\n<option value="24">24</option>\n<option value="25">25</option>\n<option value="26">26</option>\n<option value="27">27</option>\n<option value="28">28</option>\n<option value="29">29</option>\n<option value="30">30</option>\n<option value="31">31</option>\n<option value="32">32</option>\n<option value="33">33</option>\n<option value="34">34</option>\n<option value="35">35</option>\n<option value="36">36</option>\n<option value="37">37</option>\n<option value="38">38</option>\n<option value="39">39</option>\n<option value="40">40</option>\n<option value="41">41</option>\n<option value="42">42</option>\n<option value="43">43</option>\n<option value="44">44</option>\n<option value="45">45</option>\n<option value="46">46</option>\n<option value="47">47</option>\n<option value="48">48</option>\n<option value="49">49</option>\n<option value="50">50</option>\n<option value="51">51</option>\n<option value="52">52</option>\n<option value="53">53</option>\n<option value="54">54</option>\n<option value="55">55</option>\n<option value="56">56</option>\n<option value="57">57</option>\n<option value="58">58</option>\n<option value="59">59</option>\n)
     expected << "</select>\n"
 
@@ -769,7 +769,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_second_with_field_name_override
-    expected = %(<select id="date_segundo" name="date[segundo]">\n)
+    expected = %(<select id="date_segundo" name="date[segundo]">\n).dup
     expected << %(<option value="00">00</option>\n<option value="01">01</option>\n<option value="02">02</option>\n<option value="03">03</option>\n<option value="04">04</option>\n<option value="05">05</option>\n<option value="06">06</option>\n<option value="07">07</option>\n<option value="08">08</option>\n<option value="09">09</option>\n<option value="10">10</option>\n<option value="11">11</option>\n<option value="12">12</option>\n<option value="13">13</option>\n<option value="14">14</option>\n<option value="15">15</option>\n<option value="16">16</option>\n<option value="17">17</option>\n<option value="18" selected="selected">18</option>\n<option value="19">19</option>\n<option value="20">20</option>\n<option value="21">21</option>\n<option value="22">22</option>\n<option value="23">23</option>\n<option value="24">24</option>\n<option value="25">25</option>\n<option value="26">26</option>\n<option value="27">27</option>\n<option value="28">28</option>\n<option value="29">29</option>\n<option value="30">30</option>\n<option value="31">31</option>\n<option value="32">32</option>\n<option value="33">33</option>\n<option value="34">34</option>\n<option value="35">35</option>\n<option value="36">36</option>\n<option value="37">37</option>\n<option value="38">38</option>\n<option value="39">39</option>\n<option value="40">40</option>\n<option value="41">41</option>\n<option value="42">42</option>\n<option value="43">43</option>\n<option value="44">44</option>\n<option value="45">45</option>\n<option value="46">46</option>\n<option value="47">47</option>\n<option value="48">48</option>\n<option value="49">49</option>\n<option value="50">50</option>\n<option value="51">51</option>\n<option value="52">52</option>\n<option value="53">53</option>\n<option value="54">54</option>\n<option value="55">55</option>\n<option value="56">56</option>\n<option value="57">57</option>\n<option value="58">58</option>\n<option value="59">59</option>\n)
     expected << "</select>\n"
 
@@ -777,7 +777,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_second_with_blank
-    expected = %(<select id="date_second" name="date[second]">\n)
+    expected = %(<select id="date_second" name="date[second]">\n).dup
     expected << %(<option value=""></option>\n<option value="00">00</option>\n<option value="01">01</option>\n<option value="02">02</option>\n<option value="03">03</option>\n<option value="04">04</option>\n<option value="05">05</option>\n<option value="06">06</option>\n<option value="07">07</option>\n<option value="08">08</option>\n<option value="09">09</option>\n<option value="10">10</option>\n<option value="11">11</option>\n<option value="12">12</option>\n<option value="13">13</option>\n<option value="14">14</option>\n<option value="15">15</option>\n<option value="16">16</option>\n<option value="17">17</option>\n<option value="18" selected="selected">18</option>\n<option value="19">19</option>\n<option value="20">20</option>\n<option value="21">21</option>\n<option value="22">22</option>\n<option value="23">23</option>\n<option value="24">24</option>\n<option value="25">25</option>\n<option value="26">26</option>\n<option value="27">27</option>\n<option value="28">28</option>\n<option value="29">29</option>\n<option value="30">30</option>\n<option value="31">31</option>\n<option value="32">32</option>\n<option value="33">33</option>\n<option value="34">34</option>\n<option value="35">35</option>\n<option value="36">36</option>\n<option value="37">37</option>\n<option value="38">38</option>\n<option value="39">39</option>\n<option value="40">40</option>\n<option value="41">41</option>\n<option value="42">42</option>\n<option value="43">43</option>\n<option value="44">44</option>\n<option value="45">45</option>\n<option value="46">46</option>\n<option value="47">47</option>\n<option value="48">48</option>\n<option value="49">49</option>\n<option value="50">50</option>\n<option value="51">51</option>\n<option value="52">52</option>\n<option value="53">53</option>\n<option value="54">54</option>\n<option value="55">55</option>\n<option value="56">56</option>\n<option value="57">57</option>\n<option value="58">58</option>\n<option value="59">59</option>\n)
     expected << "</select>\n"
 
@@ -785,7 +785,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_second_nil_with_blank
-    expected = %(<select id="date_second" name="date[second]">\n)
+    expected = %(<select id="date_second" name="date[second]">\n).dup
     expected << %(<option value=""></option>\n<option value="00">00</option>\n<option value="01">01</option>\n<option value="02">02</option>\n<option value="03">03</option>\n<option value="04">04</option>\n<option value="05">05</option>\n<option value="06">06</option>\n<option value="07">07</option>\n<option value="08">08</option>\n<option value="09">09</option>\n<option value="10">10</option>\n<option value="11">11</option>\n<option value="12">12</option>\n<option value="13">13</option>\n<option value="14">14</option>\n<option value="15">15</option>\n<option value="16">16</option>\n<option value="17">17</option>\n<option value="18">18</option>\n<option value="19">19</option>\n<option value="20">20</option>\n<option value="21">21</option>\n<option value="22">22</option>\n<option value="23">23</option>\n<option value="24">24</option>\n<option value="25">25</option>\n<option value="26">26</option>\n<option value="27">27</option>\n<option value="28">28</option>\n<option value="29">29</option>\n<option value="30">30</option>\n<option value="31">31</option>\n<option value="32">32</option>\n<option value="33">33</option>\n<option value="34">34</option>\n<option value="35">35</option>\n<option value="36">36</option>\n<option value="37">37</option>\n<option value="38">38</option>\n<option value="39">39</option>\n<option value="40">40</option>\n<option value="41">41</option>\n<option value="42">42</option>\n<option value="43">43</option>\n<option value="44">44</option>\n<option value="45">45</option>\n<option value="46">46</option>\n<option value="47">47</option>\n<option value="48">48</option>\n<option value="49">49</option>\n<option value="50">50</option>\n<option value="51">51</option>\n<option value="52">52</option>\n<option value="53">53</option>\n<option value="54">54</option>\n<option value="55">55</option>\n<option value="56">56</option>\n<option value="57">57</option>\n<option value="58">58</option>\n<option value="59">59</option>\n)
     expected << "</select>\n"
 
@@ -793,7 +793,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_second_with_html_options
-    expected = %(<select id="date_second" name="date[second]" class="selector" accesskey="M">\n)
+    expected = %(<select id="date_second" name="date[second]" class="selector" accesskey="M">\n).dup
     expected << %(<option value="00">00</option>\n<option value="01">01</option>\n<option value="02">02</option>\n<option value="03">03</option>\n<option value="04">04</option>\n<option value="05">05</option>\n<option value="06">06</option>\n<option value="07">07</option>\n<option value="08">08</option>\n<option value="09">09</option>\n<option value="10">10</option>\n<option value="11">11</option>\n<option value="12">12</option>\n<option value="13">13</option>\n<option value="14">14</option>\n<option value="15">15</option>\n<option value="16">16</option>\n<option value="17">17</option>\n<option value="18" selected="selected">18</option>\n<option value="19">19</option>\n<option value="20">20</option>\n<option value="21">21</option>\n<option value="22">22</option>\n<option value="23">23</option>\n<option value="24">24</option>\n<option value="25">25</option>\n<option value="26">26</option>\n<option value="27">27</option>\n<option value="28">28</option>\n<option value="29">29</option>\n<option value="30">30</option>\n<option value="31">31</option>\n<option value="32">32</option>\n<option value="33">33</option>\n<option value="34">34</option>\n<option value="35">35</option>\n<option value="36">36</option>\n<option value="37">37</option>\n<option value="38">38</option>\n<option value="39">39</option>\n<option value="40">40</option>\n<option value="41">41</option>\n<option value="42">42</option>\n<option value="43">43</option>\n<option value="44">44</option>\n<option value="45">45</option>\n<option value="46">46</option>\n<option value="47">47</option>\n<option value="48">48</option>\n<option value="49">49</option>\n<option value="50">50</option>\n<option value="51">51</option>\n<option value="52">52</option>\n<option value="53">53</option>\n<option value="54">54</option>\n<option value="55">55</option>\n<option value="56">56</option>\n<option value="57">57</option>\n<option value="58">58</option>\n<option value="59">59</option>\n)
     expected << "</select>\n"
 
@@ -801,7 +801,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_second_with_default_prompt
-    expected = %(<select id="date_second" name="date[second]">\n)
+    expected = %(<select id="date_second" name="date[second]">\n).dup
     expected << %(<option value="">Seconds</option>\n<option value="00">00</option>\n<option value="01">01</option>\n<option value="02">02</option>\n<option value="03">03</option>\n<option value="04">04</option>\n<option value="05">05</option>\n<option value="06">06</option>\n<option value="07">07</option>\n<option value="08">08</option>\n<option value="09">09</option>\n<option value="10">10</option>\n<option value="11">11</option>\n<option value="12">12</option>\n<option value="13">13</option>\n<option value="14">14</option>\n<option value="15">15</option>\n<option value="16">16</option>\n<option value="17">17</option>\n<option value="18" selected="selected">18</option>\n<option value="19">19</option>\n<option value="20">20</option>\n<option value="21">21</option>\n<option value="22">22</option>\n<option value="23">23</option>\n<option value="24">24</option>\n<option value="25">25</option>\n<option value="26">26</option>\n<option value="27">27</option>\n<option value="28">28</option>\n<option value="29">29</option>\n<option value="30">30</option>\n<option value="31">31</option>\n<option value="32">32</option>\n<option value="33">33</option>\n<option value="34">34</option>\n<option value="35">35</option>\n<option value="36">36</option>\n<option value="37">37</option>\n<option value="38">38</option>\n<option value="39">39</option>\n<option value="40">40</option>\n<option value="41">41</option>\n<option value="42">42</option>\n<option value="43">43</option>\n<option value="44">44</option>\n<option value="45">45</option>\n<option value="46">46</option>\n<option value="47">47</option>\n<option value="48">48</option>\n<option value="49">49</option>\n<option value="50">50</option>\n<option value="51">51</option>\n<option value="52">52</option>\n<option value="53">53</option>\n<option value="54">54</option>\n<option value="55">55</option>\n<option value="56">56</option>\n<option value="57">57</option>\n<option value="58">58</option>\n<option value="59">59</option>\n)
     expected << "</select>\n"
 
@@ -809,7 +809,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_second_with_custom_prompt
-    expected = %(<select id="date_second" name="date[second]">\n)
+    expected = %(<select id="date_second" name="date[second]">\n).dup
     expected << %(<option value="">Choose seconds</option>\n<option value="00">00</option>\n<option value="01">01</option>\n<option value="02">02</option>\n<option value="03">03</option>\n<option value="04">04</option>\n<option value="05">05</option>\n<option value="06">06</option>\n<option value="07">07</option>\n<option value="08">08</option>\n<option value="09">09</option>\n<option value="10">10</option>\n<option value="11">11</option>\n<option value="12">12</option>\n<option value="13">13</option>\n<option value="14">14</option>\n<option value="15">15</option>\n<option value="16">16</option>\n<option value="17">17</option>\n<option value="18" selected="selected">18</option>\n<option value="19">19</option>\n<option value="20">20</option>\n<option value="21">21</option>\n<option value="22">22</option>\n<option value="23">23</option>\n<option value="24">24</option>\n<option value="25">25</option>\n<option value="26">26</option>\n<option value="27">27</option>\n<option value="28">28</option>\n<option value="29">29</option>\n<option value="30">30</option>\n<option value="31">31</option>\n<option value="32">32</option>\n<option value="33">33</option>\n<option value="34">34</option>\n<option value="35">35</option>\n<option value="36">36</option>\n<option value="37">37</option>\n<option value="38">38</option>\n<option value="39">39</option>\n<option value="40">40</option>\n<option value="41">41</option>\n<option value="42">42</option>\n<option value="43">43</option>\n<option value="44">44</option>\n<option value="45">45</option>\n<option value="46">46</option>\n<option value="47">47</option>\n<option value="48">48</option>\n<option value="49">49</option>\n<option value="50">50</option>\n<option value="51">51</option>\n<option value="52">52</option>\n<option value="53">53</option>\n<option value="54">54</option>\n<option value="55">55</option>\n<option value="56">56</option>\n<option value="57">57</option>\n<option value="58">58</option>\n<option value="59">59</option>\n)
     expected << "</select>\n"
 
@@ -817,7 +817,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_second_with_generic_with_css_classes
-    expected = %(<select id="date_second" name="date[second]" class="second">\n)
+    expected = %(<select id="date_second" name="date[second]" class="second">\n).dup
     expected << %(<option value="00">00</option>\n<option value="01">01</option>\n<option value="02">02</option>\n<option value="03">03</option>\n<option value="04">04</option>\n<option value="05">05</option>\n<option value="06">06</option>\n<option value="07">07</option>\n<option value="08">08</option>\n<option value="09">09</option>\n<option value="10">10</option>\n<option value="11">11</option>\n<option value="12">12</option>\n<option value="13">13</option>\n<option value="14">14</option>\n<option value="15">15</option>\n<option value="16">16</option>\n<option value="17">17</option>\n<option value="18" selected="selected">18</option>\n<option value="19">19</option>\n<option value="20">20</option>\n<option value="21">21</option>\n<option value="22">22</option>\n<option value="23">23</option>\n<option value="24">24</option>\n<option value="25">25</option>\n<option value="26">26</option>\n<option value="27">27</option>\n<option value="28">28</option>\n<option value="29">29</option>\n<option value="30">30</option>\n<option value="31">31</option>\n<option value="32">32</option>\n<option value="33">33</option>\n<option value="34">34</option>\n<option value="35">35</option>\n<option value="36">36</option>\n<option value="37">37</option>\n<option value="38">38</option>\n<option value="39">39</option>\n<option value="40">40</option>\n<option value="41">41</option>\n<option value="42">42</option>\n<option value="43">43</option>\n<option value="44">44</option>\n<option value="45">45</option>\n<option value="46">46</option>\n<option value="47">47</option>\n<option value="48">48</option>\n<option value="49">49</option>\n<option value="50">50</option>\n<option value="51">51</option>\n<option value="52">52</option>\n<option value="53">53</option>\n<option value="54">54</option>\n<option value="55">55</option>\n<option value="56">56</option>\n<option value="57">57</option>\n<option value="58">58</option>\n<option value="59">59</option>\n)
     expected << "</select>\n"
 
@@ -825,7 +825,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_second_with_custom_with_css_classes
-    expected = %(<select id="date_second" name="date[second]" class="my-second">\n)
+    expected = %(<select id="date_second" name="date[second]" class="my-second">\n).dup
     expected << %(<option value="00">00</option>\n<option value="01">01</option>\n<option value="02">02</option>\n<option value="03">03</option>\n<option value="04">04</option>\n<option value="05">05</option>\n<option value="06">06</option>\n<option value="07">07</option>\n<option value="08">08</option>\n<option value="09">09</option>\n<option value="10">10</option>\n<option value="11">11</option>\n<option value="12">12</option>\n<option value="13">13</option>\n<option value="14">14</option>\n<option value="15">15</option>\n<option value="16">16</option>\n<option value="17">17</option>\n<option value="18" selected="selected">18</option>\n<option value="19">19</option>\n<option value="20">20</option>\n<option value="21">21</option>\n<option value="22">22</option>\n<option value="23">23</option>\n<option value="24">24</option>\n<option value="25">25</option>\n<option value="26">26</option>\n<option value="27">27</option>\n<option value="28">28</option>\n<option value="29">29</option>\n<option value="30">30</option>\n<option value="31">31</option>\n<option value="32">32</option>\n<option value="33">33</option>\n<option value="34">34</option>\n<option value="35">35</option>\n<option value="36">36</option>\n<option value="37">37</option>\n<option value="38">38</option>\n<option value="39">39</option>\n<option value="40">40</option>\n<option value="41">41</option>\n<option value="42">42</option>\n<option value="43">43</option>\n<option value="44">44</option>\n<option value="45">45</option>\n<option value="46">46</option>\n<option value="47">47</option>\n<option value="48">48</option>\n<option value="49">49</option>\n<option value="50">50</option>\n<option value="51">51</option>\n<option value="52">52</option>\n<option value="53">53</option>\n<option value="54">54</option>\n<option value="55">55</option>\n<option value="56">56</option>\n<option value="57">57</option>\n<option value="58">58</option>\n<option value="59">59</option>\n)
     expected << "</select>\n"
 
@@ -833,7 +833,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_date
-    expected =  %(<select id="date_first_year" name="date[first][year]">\n)
+    expected =  %(<select id="date_first_year" name="date[first][year]">\n).dup
     expected << %(<option value="2003" selected="selected">2003</option>\n<option value="2004">2004</option>\n<option value="2005">2005</option>\n)
     expected << "</select>\n"
 
@@ -858,7 +858,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_date_with_order
-    expected = %(<select id="date_first_month" name="date[first][month]">\n)
+    expected = %(<select id="date_first_month" name="date[first][month]">\n).dup
     expected << %(<option value="1">January</option>\n<option value="2">February</option>\n<option value="3">March</option>\n<option value="4">April</option>\n<option value="5">May</option>\n<option value="6">June</option>\n<option value="7">July</option>\n<option value="8" selected="selected">August</option>\n<option value="9">September</option>\n<option value="10">October</option>\n<option value="11">November</option>\n<option value="12">December</option>\n)
     expected << "</select>\n"
 
@@ -875,7 +875,7 @@ class DateHelperTest < ActionView::TestCase
 
   def test_select_date_with_incomplete_order
     # Since the order is incomplete nothing will be shown
-    expected = %(<input id="date_first_year" name="date[first][year]" type="hidden" value="2003" />\n)
+    expected = %(<input id="date_first_year" name="date[first][year]" type="hidden" value="2003" />\n).dup
     expected << %(<input id="date_first_month" name="date[first][month]" type="hidden" value="8" />\n)
     expected << %(<input id="date_first_day" name="date[first][day]" type="hidden" value="1" />\n)
 
@@ -883,7 +883,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_date_with_disabled
-    expected =  %(<select id="date_first_year" name="date[first][year]" disabled="disabled">\n)
+    expected =  %(<select id="date_first_year" name="date[first][year]" disabled="disabled">\n).dup
     expected << %(<option value="2003" selected="selected">2003</option>\n<option value="2004">2004</option>\n<option value="2005">2005</option>\n)
     expected << "</select>\n"
 
@@ -899,7 +899,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_date_with_no_start_year
-    expected = %(<select id="date_first_year" name="date[first][year]">\n)
+    expected = %(<select id="date_first_year" name="date[first][year]">\n).dup
     (Date.today.year - 5).upto(Date.today.year + 1) do |y|
       if y == Date.today.year
         expected << %(<option value="#{y}" selected="selected">#{y}</option>\n)
@@ -923,7 +923,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_date_with_no_end_year
-    expected = %(<select id="date_first_year" name="date[first][year]">\n)
+    expected = %(<select id="date_first_year" name="date[first][year]">\n).dup
     2003.upto(2008) do |y|
       if y == 2003
         expected << %(<option value="#{y}" selected="selected">#{y}</option>\n)
@@ -947,7 +947,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_date_with_no_start_or_end_year
-    expected = %(<select id="date_first_year" name="date[first][year]">\n)
+    expected = %(<select id="date_first_year" name="date[first][year]">\n).dup
     (Date.today.year - 5).upto(Date.today.year + 5) do |y|
       if y == Date.today.year
         expected << %(<option value="#{y}" selected="selected">#{y}</option>\n)
@@ -971,7 +971,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_date_with_zero_value
-    expected =  %(<select id="date_first_year" name="date[first][year]">\n)
+    expected =  %(<select id="date_first_year" name="date[first][year]">\n).dup
     expected << %(<option value="2003">2003</option>\n<option value="2004">2004</option>\n<option value="2005">2005</option>\n)
     expected << "</select>\n"
 
@@ -987,7 +987,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_date_with_zero_value_and_no_start_year
-    expected = %(<select id="date_first_year" name="date[first][year]">\n)
+    expected = %(<select id="date_first_year" name="date[first][year]">\n).dup
     (Date.today.year - 5).upto(Date.today.year + 1) { |y| expected << %(<option value="#{y}">#{y}</option>\n) }
     expected << "</select>\n"
 
@@ -1003,7 +1003,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_date_with_zero_value_and_no_end_year
-    expected =  %(<select id="date_first_year" name="date[first][year]">\n)
+    expected =  %(<select id="date_first_year" name="date[first][year]">\n).dup
     last_year = Time.now.year + 5
     2003.upto(last_year) { |y| expected << %(<option value="#{y}">#{y}</option>\n) }
     expected << "</select>\n"
@@ -1020,7 +1020,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_date_with_zero_value_and_no_start_and_end_year
-    expected = %(<select id="date_first_year" name="date[first][year]">\n)
+    expected = %(<select id="date_first_year" name="date[first][year]">\n).dup
     (Date.today.year - 5).upto(Date.today.year + 5) { |y| expected << %(<option value="#{y}">#{y}</option>\n) }
     expected << "</select>\n"
 
@@ -1036,7 +1036,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_date_with_nil_value_and_no_start_and_end_year
-    expected = %(<select id="date_first_year" name="date[first][year]">\n)
+    expected = %(<select id="date_first_year" name="date[first][year]">\n).dup
     (Date.today.year - 5).upto(Date.today.year + 5) { |y| expected << %(<option value="#{y}">#{y}</option>\n) }
     expected << "</select>\n"
 
@@ -1052,7 +1052,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_date_with_html_options
-    expected =  %(<select id="date_first_year" name="date[first][year]" class="selector">\n)
+    expected =  %(<select id="date_first_year" name="date[first][year]" class="selector">\n).dup
     expected << %(<option value="2003" selected="selected">2003</option>\n<option value="2004">2004</option>\n<option value="2005">2005</option>\n)
     expected << "</select>\n"
 
@@ -1068,7 +1068,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_date_with_separator
-    expected =  %(<select id="date_first_year" name="date[first][year]">\n)
+    expected =  %(<select id="date_first_year" name="date[first][year]">\n).dup
     expected << %(<option value="2003" selected="selected">2003</option>\n<option value="2004">2004</option>\n<option value="2005">2005</option>\n)
     expected << "</select>\n"
 
@@ -1088,7 +1088,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_date_with_separator_and_discard_day
-    expected =  %(<select id="date_first_year" name="date[first][year]">\n)
+    expected =  %(<select id="date_first_year" name="date[first][year]">\n).dup
     expected << %(<option value="2003" selected="selected">2003</option>\n<option value="2004">2004</option>\n<option value="2005">2005</option>\n)
     expected << "</select>\n"
 
@@ -1104,7 +1104,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_date_with_separator_discard_month_and_day
-    expected =  %(<select id="date_first_year" name="date[first][year]">\n)
+    expected =  %(<select id="date_first_year" name="date[first][year]">\n).dup
     expected << %(<option value="2003" selected="selected">2003</option>\n<option value="2004">2004</option>\n<option value="2005">2005</option>\n)
     expected << "</select>\n"
 
@@ -1115,7 +1115,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_date_with_hidden
-    expected =  %(<input id="date_first_year" name="date[first][year]" type="hidden" value="2003"/>\n)
+    expected =  %(<input id="date_first_year" name="date[first][year]" type="hidden" value="2003"/>\n).dup
     expected << %(<input id="date_first_month" name="date[first][month]" type="hidden" value="8" />\n)
     expected << %(<input id="date_first_day" name="date[first][day]" type="hidden" value="16" />\n)
 
@@ -1124,7 +1124,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_date_with_css_classes_option
-    expected =  %(<select id="date_first_year" name="date[first][year]" class="year">\n)
+    expected =  %(<select id="date_first_year" name="date[first][year]" class="year">\n).dup
     expected << %(<option value="2003" selected="selected">2003</option>\n<option value="2004">2004</option>\n<option value="2005">2005</option>\n)
     expected << "</select>\n"
 
@@ -1140,7 +1140,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_date_with_custom_with_css_classes
-    expected =  %(<select id="date_year" name="date[year]" class="my-year">\n)
+    expected =  %(<select id="date_year" name="date[year]" class="my-year">\n).dup
     expected << %(<option value="2003" selected="selected">2003</option>\n<option value="2004">2004</option>\n<option value="2005">2005</option>\n)
     expected << "</select>\n"
 
@@ -1156,7 +1156,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_date_with_css_classes_option_and_html_class_option
-    expected =  %(<select id="date_first_year" name="date[first][year]" class="datetime optional year">\n)
+    expected =  %(<select id="date_first_year" name="date[first][year]" class="datetime optional year">\n).dup
     expected << %(<option value="2003" selected="selected">2003</option>\n<option value="2004">2004</option>\n<option value="2005">2005</option>\n)
     expected << "</select>\n"
 
@@ -1172,7 +1172,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_date_with_custom_with_css_classes_and_html_class_option
-    expected =  %(<select id="date_year" name="date[year]" class="date optional my-year">\n)
+    expected =  %(<select id="date_year" name="date[year]" class="date optional my-year">\n).dup
     expected << %(<option value="2003" selected="selected">2003</option>\n<option value="2004">2004</option>\n<option value="2005">2005</option>\n)
     expected << "</select>\n"
 
@@ -1188,7 +1188,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_date_with_partial_with_css_classes_and_html_class_option
-    expected =  %(<select id="date_year" name="date[year]" class="date optional">\n)
+    expected =  %(<select id="date_year" name="date[year]" class="date optional">\n).dup
     expected << %(<option value="2003" selected="selected">2003</option>\n<option value="2004">2004</option>\n<option value="2005">2005</option>\n)
     expected << "</select>\n"
 
@@ -1204,7 +1204,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_date_with_html_class_option
-    expected =  %(<select id="date_year" name="date[year]" class="date optional custom-grid">\n)
+    expected =  %(<select id="date_year" name="date[year]" class="date optional custom-grid">\n).dup
     expected << %(<option value="2003" selected="selected">2003</option>\n<option value="2004">2004</option>\n<option value="2005">2005</option>\n)
     expected << "</select>\n"
 
@@ -1220,7 +1220,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_datetime
-    expected =  %(<select id="date_first_year" name="date[first][year]">\n)
+    expected =  %(<select id="date_first_year" name="date[first][year]">\n).dup
     expected << %(<option value="2003" selected="selected">2003</option>\n<option value="2004">2004</option>\n<option value="2005">2005</option>\n)
     expected << "</select>\n"
 
@@ -1248,7 +1248,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_datetime_with_ampm
-    expected =  %(<select id="date_first_year" name="date[first][year]">\n)
+    expected =  %(<select id="date_first_year" name="date[first][year]">\n).dup
     expected << %(<option value="2003" selected="selected">2003</option>\n<option value="2004">2004</option>\n<option value="2005">2005</option>\n)
     expected << "</select>\n"
 
@@ -1276,7 +1276,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_datetime_with_separators
-    expected =  %(<select id="date_first_year" name="date[first][year]">\n)
+    expected =  %(<select id="date_first_year" name="date[first][year]">\n).dup
     expected << %(<option value="2003" selected="selected">2003</option>\n<option value="2004">2004</option>\n<option value="2005">2005</option>\n)
     expected << "</select>\n"
 
@@ -1304,7 +1304,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_datetime_with_nil_value_and_no_start_and_end_year
-    expected = %(<select id="date_first_year" name="date[first][year]">\n)
+    expected = %(<select id="date_first_year" name="date[first][year]">\n).dup
     (Date.today.year - 5).upto(Date.today.year + 5) { |y| expected << %(<option value="#{y}">#{y}</option>\n) }
     expected << "</select>\n"
 
@@ -1332,7 +1332,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_datetime_with_html_options
-    expected =  %(<select id="date_first_year" name="date[first][year]" class="selector">\n)
+    expected =  %(<select id="date_first_year" name="date[first][year]" class="selector">\n).dup
     expected << %(<option value="2003" selected="selected">2003</option>\n<option value="2004">2004</option>\n<option value="2005">2005</option>\n)
     expected << "</select>\n"
 
@@ -1360,7 +1360,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_datetime_with_all_separators
-    expected =  %(<select id="date_first_year" name="date[first][year]" class="selector">\n)
+    expected =  %(<select id="date_first_year" name="date[first][year]" class="selector">\n).dup
     expected << %(<option value="2003" selected="selected">2003</option>\n<option value="2004">2004</option>\n<option value="2005">2005</option>\n)
     expected << "</select>\n"
 
@@ -1396,7 +1396,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_datetime_with_default_prompt
-    expected =  %(<select id="date_first_year" name="date[first][year]">\n)
+    expected =  %(<select id="date_first_year" name="date[first][year]">\n).dup
     expected << %(<option value="">Year</option>\n<option value="2003" selected="selected">2003</option>\n<option value="2004">2004</option>\n<option value="2005">2005</option>\n)
     expected << "</select>\n"
 
@@ -1425,7 +1425,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_datetime_with_custom_prompt
-    expected =  %(<select id="date_first_year" name="date[first][year]">\n)
+    expected =  %(<select id="date_first_year" name="date[first][year]">\n).dup
     expected << %(<option value="">Choose year</option>\n<option value="2003" selected="selected">2003</option>\n<option value="2004">2004</option>\n<option value="2005">2005</option>\n)
     expected << "</select>\n"
 
@@ -1454,7 +1454,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_datetime_with_generic_with_css_classes
-    expected =  %(<select id="date_year" name="date[year]" class="year">\n)
+    expected =  %(<select id="date_year" name="date[year]" class="year">\n).dup
     expected << %(<option value="2003" selected="selected">2003</option>\n<option value="2004">2004</option>\n<option value="2005">2005</option>\n)
     expected << "</select>\n"
 
@@ -1482,7 +1482,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_datetime_with_custom_with_css_classes
-    expected =  %(<select id="date_year" name="date[year]" class="my-year">\n)
+    expected =  %(<select id="date_year" name="date[year]" class="my-year">\n).dup
     expected << %(<option value="2003" selected="selected">2003</option>\n<option value="2004">2004</option>\n<option value="2005">2005</option>\n)
     expected << "</select>\n"
 
@@ -1510,7 +1510,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_datetime_with_custom_hours
-    expected =  %(<select id="date_first_year" name="date[first][year]">\n)
+    expected =  %(<select id="date_first_year" name="date[first][year]">\n).dup
     expected << %(<option value="">Choose year</option>\n<option value="2003" selected="selected">2003</option>\n<option value="2004">2004</option>\n<option value="2005">2005</option>\n)
     expected << "</select>\n"
 
@@ -1539,7 +1539,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_datetime_with_hidden
-    expected =  %(<input id="date_first_year" name="date[first][year]" type="hidden" value="2003" />\n)
+    expected =  %(<input id="date_first_year" name="date[first][year]" type="hidden" value="2003" />\n).dup
     expected << %(<input id="date_first_month" name="date[first][month]" type="hidden" value="8" />\n)
     expected << %(<input id="date_first_day" name="date[first][day]" type="hidden" value="16" />\n)
     expected << %(<input id="date_first_hour" name="date[first][hour]" type="hidden" value="8" />\n)
@@ -1551,7 +1551,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_time
-    expected = %(<input name="date[year]" id="date_year" value="2003" type="hidden" />\n)
+    expected = %(<input name="date[year]" id="date_year" value="2003" type="hidden" />\n).dup
     expected << %(<input name="date[month]" id="date_month" value="8" type="hidden" />\n)
     expected << %(<input name="date[day]" id="date_day" value="16" type="hidden" />\n)
 
@@ -1570,7 +1570,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_time_with_ampm
-    expected = %(<input name="date[year]" id="date_year" value="2003" type="hidden" />\n)
+    expected = %(<input name="date[year]" id="date_year" value="2003" type="hidden" />\n).dup
     expected << %(<input name="date[month]" id="date_month" value="8" type="hidden" />\n)
     expected << %(<input name="date[day]" id="date_day" value="16" type="hidden" />\n)
 
@@ -1588,7 +1588,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_time_with_separator
-    expected = %(<input name="date[year]" id="date_year" value="2003" type="hidden" />\n)
+    expected = %(<input name="date[year]" id="date_year" value="2003" type="hidden" />\n).dup
     expected << %(<input name="date[month]" id="date_month" value="8" type="hidden" />\n)
     expected << %(<input name="date[day]" id="date_day" value="16" type="hidden" />\n)
     expected << %(<select id="date_hour" name="date[hour]">\n)
@@ -1606,7 +1606,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_time_with_seconds
-    expected = %(<input name="date[year]" id="date_year" value="2003" type="hidden" />\n)
+    expected = %(<input name="date[year]" id="date_year" value="2003" type="hidden" />\n).dup
     expected << %(<input name="date[month]" id="date_month" value="8" type="hidden" />\n)
     expected << %(<input name="date[day]" id="date_day" value="16" type="hidden" />\n)
 
@@ -1630,7 +1630,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_time_with_seconds_and_separator
-    expected = %(<input name="date[year]" id="date_year" value="2003" type="hidden" />\n)
+    expected = %(<input name="date[year]" id="date_year" value="2003" type="hidden" />\n).dup
     expected << %(<input name="date[month]" id="date_month" value="8" type="hidden" />\n)
     expected << %(<input name="date[day]" id="date_day" value="16" type="hidden" />\n)
 
@@ -1654,7 +1654,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_time_with_html_options
-    expected = %(<input name="date[year]" id="date_year" value="2003" type="hidden" />\n)
+    expected = %(<input name="date[year]" id="date_year" value="2003" type="hidden" />\n).dup
     expected << %(<input name="date[month]" id="date_month" value="8" type="hidden" />\n)
     expected << %(<input name="date[day]" id="date_day" value="16" type="hidden" />\n)
 
@@ -1677,7 +1677,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_time_with_default_prompt
-    expected = %(<input name="date[year]" id="date_year" value="2003" type="hidden" />\n)
+    expected = %(<input name="date[year]" id="date_year" value="2003" type="hidden" />\n).dup
     expected << %(<input name="date[month]" id="date_month" value="8" type="hidden" />\n)
     expected << %(<input name="date[day]" id="date_day" value="16" type="hidden" />\n)
 
@@ -1701,7 +1701,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_time_with_custom_prompt
-    expected = %(<input name="date[year]" id="date_year" value="2003" type="hidden" />\n)
+    expected = %(<input name="date[year]" id="date_year" value="2003" type="hidden" />\n).dup
     expected << %(<input name="date[month]" id="date_month" value="8" type="hidden" />\n)
     expected << %(<input name="date[day]" id="date_day" value="16" type="hidden" />\n)
 
@@ -1726,7 +1726,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_time_with_generic_with_css_classes
-    expected = %(<input name="date[year]" id="date_year" value="2003" type="hidden" />\n)
+    expected = %(<input name="date[year]" id="date_year" value="2003" type="hidden" />\n).dup
     expected << %(<input name="date[month]" id="date_month" value="8" type="hidden" />\n)
     expected << %(<input name="date[day]" id="date_day" value="16" type="hidden" />\n)
 
@@ -1750,7 +1750,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_time_with_custom_with_css_classes
-    expected = %(<input name="date[year]" id="date_year" value="2003" type="hidden" />\n)
+    expected = %(<input name="date[year]" id="date_year" value="2003" type="hidden" />\n).dup
     expected << %(<input name="date[month]" id="date_month" value="8" type="hidden" />\n)
     expected << %(<input name="date[day]" id="date_day" value="16" type="hidden" />\n)
 
@@ -1774,7 +1774,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_select_time_with_hidden
-    expected =  %(<input id="date_first_year" name="date[first][year]" type="hidden" value="2003" />\n)
+    expected =  %(<input id="date_first_year" name="date[first][year]" type="hidden" value="2003" />\n).dup
     expected << %(<input id="date_first_month" name="date[first][month]" type="hidden" value="8" />\n)
     expected << %(<input id="date_first_day" name="date[first][day]" type="hidden" value="16" />\n)
     expected << %(<input id="date_first_hour" name="date[first][hour]" type="hidden" value="8" />\n)
@@ -1788,7 +1788,7 @@ class DateHelperTest < ActionView::TestCase
     @post = Post.new
     @post.written_on = Date.new(2004, 6, 15)
 
-    expected = %{<select id="post_written_on_1i" name="post[written_on(1i)]">\n}
+    expected = %{<select id="post_written_on_1i" name="post[written_on(1i)]">\n}.dup
     expected << %{<option value="1999">1999</option>\n<option value="2000">2000</option>\n<option value="2001">2001</option>\n<option value="2002">2002</option>\n<option value="2003">2003</option>\n<option value="2004" selected="selected">2004</option>\n<option value="2005">2005</option>\n<option value="2006">2006</option>\n<option value="2007">2007</option>\n<option value="2008">2008</option>\n<option value="2009">2009</option>\n}
     expected << "</select>\n"
 
@@ -1808,7 +1808,7 @@ class DateHelperTest < ActionView::TestCase
     @post = Post.new
     @post.written_on = Date.new(2004, 6, 15)
 
-    expected = %{<select id="post_written_on_1i" name="post[written_on(1i)]">\n}
+    expected = %{<select id="post_written_on_1i" name="post[written_on(1i)]">\n}.dup
     expected << %{<option value="1999">1999</option>\n<option value="2000">2000</option>\n<option value="2001">2001</option>\n<option value="2002">2002</option>\n<option value="2003">2003</option>\n<option selected="selected" value="2004">2004</option>\n<option value="2005">2005</option>\n<option value="2006">2006</option>\n<option value="2007">2007</option>\n<option value="2008">2008</option>\n<option value="2009">2009</option>\n}
     expected << "</select>\n"
 
@@ -1828,7 +1828,7 @@ class DateHelperTest < ActionView::TestCase
     @post = Post.new
     @post.written_on = Date.new(2004, 6, 15)
 
-    expected = %{<select id="post_written_on_1i" name="post[written_on(1i)]">\n}
+    expected = %{<select id="post_written_on_1i" name="post[written_on(1i)]">\n}.dup
     expected << %{<option value="1999">1999</option>\n<option value="2000">2000</option>\n<option value="2001">2001</option>\n<option value="2002">2002</option>\n<option value="2003">2003</option>\n<option selected="selected" value="2004">2004</option>\n<option value="2005">2005</option>\n<option value="2006">2006</option>\n<option value="2007">2007</option>\n<option value="2008">2008</option>\n<option value="2009">2009</option>\n}
     expected << "</select>\n"
 
@@ -1866,7 +1866,7 @@ class DateHelperTest < ActionView::TestCase
     @post = Post.new
     @post.written_on = Date.new(2004, 6, 15)
 
-    expected = "<input type=\"hidden\" id=\"post_written_on_3i\" name=\"post[written_on(3i)]\" value=\"1\" />\n"
+    expected = "<input type=\"hidden\" id=\"post_written_on_3i\" name=\"post[written_on(3i)]\" value=\"1\" />\n".dup
 
     expected << %{<select id="post_written_on_2i" name="post[written_on(2i)]">\n}
     expected << %{<option value="1">January</option>\n<option value="2">February</option>\n<option value="3">March</option>\n<option value="4">April</option>\n<option value="5">May</option>\n<option value="6" selected="selected">June</option>\n<option value="7">July</option>\n<option value="8">August</option>\n<option value="9">September</option>\n<option value="10">October</option>\n<option value="11">November</option>\n<option value="12">December</option>\n}
@@ -1883,7 +1883,7 @@ class DateHelperTest < ActionView::TestCase
     @post = Post.new
     @post.written_on = Date.new(2004, 2, 29)
 
-    expected = "<input type=\"hidden\" id=\"post_written_on_2i\" name=\"post[written_on(2i)]\" value=\"2\" />\n"
+    expected = "<input type=\"hidden\" id=\"post_written_on_2i\" name=\"post[written_on(2i)]\" value=\"2\" />\n".dup
     expected << "<input type=\"hidden\" id=\"post_written_on_3i\" name=\"post[written_on(3i)]\" value=\"1\" />\n"
 
     expected << %{<select id="post_written_on_1i" name="post[written_on(1i)]">\n}
@@ -1897,7 +1897,7 @@ class DateHelperTest < ActionView::TestCase
     @post = Post.new
     @post.written_on = Date.new(2004, 6, 15)
 
-    expected = "<input type=\"hidden\" id=\"post_written_on_3i\" name=\"post[written_on(3i)]\" value=\"1\" />\n"
+    expected = "<input type=\"hidden\" id=\"post_written_on_3i\" name=\"post[written_on(3i)]\" value=\"1\" />\n".dup
 
     expected << %{<select id="post_written_on_2i" name="post[written_on(2i)]">\n}
     expected << %{<option value="1">January</option>\n<option value="2">February</option>\n<option value="3">March</option>\n<option value="4">April</option>\n<option value="5">May</option>\n<option value="6" selected="selected">June</option>\n<option value="7">July</option>\n<option value="8">August</option>\n<option value="9">September</option>\n<option value="10">October</option>\n<option value="11">November</option>\n<option value="12">December</option>\n}
@@ -1916,7 +1916,7 @@ class DateHelperTest < ActionView::TestCase
     @post = Post.new
     @post.written_on = Date.new(2004, 6, 15)
 
-    expected = "<input type=\"hidden\" id=\"post_written_on_3i\" disabled=\"disabled\" name=\"post[written_on(3i)]\" value=\"1\" />\n"
+    expected = "<input type=\"hidden\" id=\"post_written_on_3i\" disabled=\"disabled\" name=\"post[written_on(3i)]\" value=\"1\" />\n".dup
 
     expected << %{<select id="post_written_on_2i" disabled="disabled" name="post[written_on(2i)]">\n}
     expected << %{<option value="1">January</option>\n<option value="2">February</option>\n<option value="3">March</option>\n<option value="4">April</option>\n<option value="5">May</option>\n<option value="6" selected="selected">June</option>\n<option value="7">July</option>\n<option value="8">August</option>\n<option value="9">September</option>\n<option value="10">October</option>\n<option value="11">November</option>\n<option value="12">December</option>\n}
@@ -1937,7 +1937,7 @@ class DateHelperTest < ActionView::TestCase
       concat f.date_select(:written_on)
     end
 
-    expected = %{<select id="post_written_on_1i" name="post[written_on(1i)]">\n<option value="1999">1999</option>\n<option value="2000">2000</option>\n<option value="2001">2001</option>\n<option value="2002">2002</option>\n<option value="2003">2003</option>\n<option selected="selected" value="2004">2004</option>\n<option value="2005">2005</option>\n<option value="2006">2006</option>\n<option value="2007">2007</option>\n<option value="2008">2008</option>\n<option value="2009">2009</option>\n</select>\n}
+    expected = %{<select id="post_written_on_1i" name="post[written_on(1i)]">\n<option value="1999">1999</option>\n<option value="2000">2000</option>\n<option value="2001">2001</option>\n<option value="2002">2002</option>\n<option value="2003">2003</option>\n<option selected="selected" value="2004">2004</option>\n<option value="2005">2005</option>\n<option value="2006">2006</option>\n<option value="2007">2007</option>\n<option value="2008">2008</option>\n<option value="2009">2009</option>\n</select>\n}.dup
     expected << %{<select id="post_written_on_2i" name="post[written_on(2i)]">\n<option value="1">January</option>\n<option value="2">February</option>\n<option value="3">March</option>\n<option value="4">April</option>\n<option value="5">May</option>\n<option selected="selected" value="6">June</option>\n<option value="7">July</option>\n<option value="8">August</option>\n<option value="9">September</option>\n<option value="10">October</option>\n<option value="11">November</option>\n<option value="12">December</option>\n</select>\n}
     expected << %{<select id="post_written_on_3i" name="post[written_on(3i)]">\n<option value="1">1</option>\n<option value="2">2</option>\n<option value="3">3</option>\n<option value="4">4</option>\n<option value="5">5</option>\n<option value="6">6</option>\n<option value="7">7</option>\n<option value="8">8</option>\n<option value="9">9</option>\n<option value="10">10</option>\n<option value="11">11</option>\n<option value="12">12</option>\n<option value="13">13</option>\n<option value="14">14</option>\n<option selected="selected" value="15">15</option>\n<option value="16">16</option>\n<option value="17">17</option>\n<option value="18">18</option>\n<option value="19">19</option>\n<option value="20">20</option>\n<option value="21">21</option>\n<option value="22">22</option>\n<option value="23">23</option>\n<option value="24">24</option>\n<option value="25">25</option>\n<option value="26">26</option>\n<option value="27">27</option>\n<option value="28">28</option>\n<option value="29">29</option>\n<option value="30">30</option>\n<option value="31">31</option>\n</select>\n}
 
@@ -1953,7 +1953,7 @@ class DateHelperTest < ActionView::TestCase
       concat f.date_select(:written_on)
     end
 
-    expected = %{<select id="post_#{id}_written_on_1i" name="post[#{id}][written_on(1i)]">\n<option value="1999">1999</option>\n<option value="2000">2000</option>\n<option value="2001">2001</option>\n<option value="2002">2002</option>\n<option value="2003">2003</option>\n<option selected="selected" value="2004">2004</option>\n<option value="2005">2005</option>\n<option value="2006">2006</option>\n<option value="2007">2007</option>\n<option value="2008">2008</option>\n<option value="2009">2009</option>\n</select>\n}
+    expected = %{<select id="post_#{id}_written_on_1i" name="post[#{id}][written_on(1i)]">\n<option value="1999">1999</option>\n<option value="2000">2000</option>\n<option value="2001">2001</option>\n<option value="2002">2002</option>\n<option value="2003">2003</option>\n<option selected="selected" value="2004">2004</option>\n<option value="2005">2005</option>\n<option value="2006">2006</option>\n<option value="2007">2007</option>\n<option value="2008">2008</option>\n<option value="2009">2009</option>\n</select>\n}.dup
     expected << %{<select id="post_#{id}_written_on_2i" name="post[#{id}][written_on(2i)]">\n<option value="1">January</option>\n<option value="2">February</option>\n<option value="3">March</option>\n<option value="4">April</option>\n<option value="5">May</option>\n<option selected="selected" value="6">June</option>\n<option value="7">July</option>\n<option value="8">August</option>\n<option value="9">September</option>\n<option value="10">October</option>\n<option value="11">November</option>\n<option value="12">December</option>\n</select>\n}
     expected << %{<select id="post_#{id}_written_on_3i" name="post[#{id}][written_on(3i)]">\n<option value="1">1</option>\n<option value="2">2</option>\n<option value="3">3</option>\n<option value="4">4</option>\n<option value="5">5</option>\n<option value="6">6</option>\n<option value="7">7</option>\n<option value="8">8</option>\n<option value="9">9</option>\n<option value="10">10</option>\n<option value="11">11</option>\n<option value="12">12</option>\n<option value="13">13</option>\n<option value="14">14</option>\n<option selected="selected" value="15">15</option>\n<option value="16">16</option>\n<option value="17">17</option>\n<option value="18">18</option>\n<option value="19">19</option>\n<option value="20">20</option>\n<option value="21">21</option>\n<option value="22">22</option>\n<option value="23">23</option>\n<option value="24">24</option>\n<option value="25">25</option>\n<option value="26">26</option>\n<option value="27">27</option>\n<option value="28">28</option>\n<option value="29">29</option>\n<option value="30">30</option>\n<option value="31">31</option>\n</select>\n}
 
@@ -1969,7 +1969,7 @@ class DateHelperTest < ActionView::TestCase
       concat f.date_select(:written_on)
     end
 
-    expected = %{<select id="post_#{id}_written_on_1i" name="post[#{id}][written_on(1i)]">\n<option value="1999">1999</option>\n<option value="2000">2000</option>\n<option value="2001">2001</option>\n<option value="2002">2002</option>\n<option value="2003">2003</option>\n<option selected="selected" value="2004">2004</option>\n<option value="2005">2005</option>\n<option value="2006">2006</option>\n<option value="2007">2007</option>\n<option value="2008">2008</option>\n<option value="2009">2009</option>\n</select>\n}
+    expected = %{<select id="post_#{id}_written_on_1i" name="post[#{id}][written_on(1i)]">\n<option value="1999">1999</option>\n<option value="2000">2000</option>\n<option value="2001">2001</option>\n<option value="2002">2002</option>\n<option value="2003">2003</option>\n<option selected="selected" value="2004">2004</option>\n<option value="2005">2005</option>\n<option value="2006">2006</option>\n<option value="2007">2007</option>\n<option value="2008">2008</option>\n<option value="2009">2009</option>\n</select>\n}.dup
     expected << %{<select id="post_#{id}_written_on_2i" name="post[#{id}][written_on(2i)]">\n<option value="1">January</option>\n<option value="2">February</option>\n<option value="3">March</option>\n<option value="4">April</option>\n<option value="5">May</option>\n<option selected="selected" value="6">June</option>\n<option value="7">July</option>\n<option value="8">August</option>\n<option value="9">September</option>\n<option value="10">October</option>\n<option value="11">November</option>\n<option value="12">December</option>\n</select>\n}
     expected << %{<select id="post_#{id}_written_on_3i" name="post[#{id}][written_on(3i)]">\n<option value="1">1</option>\n<option value="2">2</option>\n<option value="3">3</option>\n<option value="4">4</option>\n<option value="5">5</option>\n<option value="6">6</option>\n<option value="7">7</option>\n<option value="8">8</option>\n<option value="9">9</option>\n<option value="10">10</option>\n<option value="11">11</option>\n<option value="12">12</option>\n<option value="13">13</option>\n<option value="14">14</option>\n<option selected="selected" value="15">15</option>\n<option value="16">16</option>\n<option value="17">17</option>\n<option value="18">18</option>\n<option value="19">19</option>\n<option value="20">20</option>\n<option value="21">21</option>\n<option value="22">22</option>\n<option value="23">23</option>\n<option value="24">24</option>\n<option value="25">25</option>\n<option value="26">26</option>\n<option value="27">27</option>\n<option value="28">28</option>\n<option value="29">29</option>\n<option value="30">30</option>\n<option value="31">31</option>\n</select>\n}
 
@@ -1981,7 +1981,7 @@ class DateHelperTest < ActionView::TestCase
     @post.written_on = Date.new(2004, 6, 15)
     id = 456
 
-    expected = %{<select id="post_456_written_on_1i" name="post[#{id}][written_on(1i)]">\n}
+    expected = %{<select id="post_456_written_on_1i" name="post[#{id}][written_on(1i)]">\n}.dup
     expected << %{<option value="1999">1999</option>\n<option value="2000">2000</option>\n<option value="2001">2001</option>\n<option value="2002">2002</option>\n<option value="2003">2003</option>\n<option value="2004" selected="selected">2004</option>\n<option value="2005">2005</option>\n<option value="2006">2006</option>\n<option value="2007">2007</option>\n<option value="2008">2008</option>\n<option value="2009">2009</option>\n}
     expected << "</select>\n"
 
@@ -2001,7 +2001,7 @@ class DateHelperTest < ActionView::TestCase
     @post.written_on = Date.new(2004, 6, 15)
     id = 123
 
-    expected = %{<select id="post_123_written_on_1i" name="post[#{id}][written_on(1i)]">\n}
+    expected = %{<select id="post_123_written_on_1i" name="post[#{id}][written_on(1i)]">\n}.dup
     expected << %{<option value="1999">1999</option>\n<option value="2000">2000</option>\n<option value="2001">2001</option>\n<option value="2002">2002</option>\n<option value="2003">2003</option>\n<option value="2004" selected="selected">2004</option>\n<option value="2005">2005</option>\n<option value="2006">2006</option>\n<option value="2007">2007</option>\n<option value="2008">2008</option>\n<option value="2009">2009</option>\n}
     expected << "</select>\n"
 
@@ -2020,7 +2020,7 @@ class DateHelperTest < ActionView::TestCase
     @post = Post.new
     @post.written_on = Date.new(2004, 6, 15)
 
-    expected = %{<select id="post_written_on_3i" name="post[written_on(3i)]">\n}
+    expected = %{<select id="post_written_on_3i" name="post[written_on(3i)]">\n}.dup
     1.upto(31) { |i| expected << %(<option value="#{i}"#{' selected="selected"' if i == 15}>#{i}</option>\n) }
     expected << "</select>\n"
 
@@ -2040,7 +2040,7 @@ class DateHelperTest < ActionView::TestCase
 
     start_year = Time.now.year - 5
     end_year   = Time.now.year + 5
-    expected =   %{<select id="post_written_on_1i" name="post[written_on(1i)]">\n}
+    expected =   %{<select id="post_written_on_1i" name="post[written_on(1i)]">\n}.dup
     start_year.upto(end_year) { |i| expected << %(<option value="#{i}"#{' selected="selected"' if i == Time.now.year}>#{i}</option>\n) }
     expected << "</select>\n"
 
@@ -2060,7 +2060,7 @@ class DateHelperTest < ActionView::TestCase
 
     start_year = Time.now.year - 5
     end_year   = Time.now.year + 5
-    expected =   %{<select id="post_written_on_1i" name="post[written_on(1i)]">\n}
+    expected =   %{<select id="post_written_on_1i" name="post[written_on(1i)]">\n}.dup
     expected << "<option value=\"\"></option>\n"
     start_year.upto(end_year) { |i| expected << %(<option value="#{i}">#{i}</option>\n) }
     expected << "</select>\n"
@@ -2104,7 +2104,7 @@ class DateHelperTest < ActionView::TestCase
     start_year = Time.now.year - 5
     end_year   = Time.now.year + 5
 
-    expected = %{<select id="post_written_on_1i" name="post[written_on(1i)]">\n}
+    expected = %{<select id="post_written_on_1i" name="post[written_on(1i)]">\n}.dup
     expected << "<option value=\"\"></option>\n"
     start_year.upto(end_year) { |i| expected << %(<option value="#{i}">#{i}</option>\n) }
     expected << "</select>\n"
@@ -2136,7 +2136,7 @@ class DateHelperTest < ActionView::TestCase
     @post = Post.new
     @post.written_on = Date.new(2004, 6, 15)
 
-    expected = %{<select id="post_written_on_1i" name="post[written_on(1i)]">\n}
+    expected = %{<select id="post_written_on_1i" name="post[written_on(1i)]">\n}.dup
     expected << %{<option value="1999">1999</option>\n<option value="2000">2000</option>\n<option value="2001">2001</option>\n<option value="2002">2002</option>\n<option value="2003">2003</option>\n<option value="2004" selected="selected">2004</option>\n<option value="2005">2005</option>\n<option value="2006">2006</option>\n<option value="2007">2007</option>\n<option value="2008">2008</option>\n<option value="2009">2009</option>\n}
     expected << "</select>\n"
 
@@ -2155,7 +2155,7 @@ class DateHelperTest < ActionView::TestCase
     @post = Post.new
     @post.written_on = Date.new(2004, 6, 15)
 
-    expected = %{<select id="post_written_on_1i" name="post[written_on(1i)]" class="selector">\n}
+    expected = %{<select id="post_written_on_1i" name="post[written_on(1i)]" class="selector">\n}.dup
     expected << %{<option value="1999">1999</option>\n<option value="2000">2000</option>\n<option value="2001">2001</option>\n<option value="2002">2002</option>\n<option value="2003">2003</option>\n<option value="2004" selected="selected">2004</option>\n<option value="2005">2005</option>\n<option value="2006">2006</option>\n<option value="2007">2007</option>\n<option value="2008">2008</option>\n<option value="2009">2009</option>\n}
     expected << "</select>\n"
 
@@ -2179,7 +2179,7 @@ class DateHelperTest < ActionView::TestCase
       concat f.date_select(:written_on, {}, class: "selector")
     end
 
-    expected = %{<select id="post_written_on_1i" name="post[written_on(1i)]" class="selector">\n}
+    expected = %{<select id="post_written_on_1i" name="post[written_on(1i)]" class="selector">\n}.dup
     expected << %{<option value="1999">1999</option>\n<option value="2000">2000</option>\n<option value="2001">2001</option>\n<option value="2002">2002</option>\n<option value="2003">2003</option>\n<option value="2004" selected="selected">2004</option>\n<option value="2005">2005</option>\n<option value="2006">2006</option>\n<option value="2007">2007</option>\n<option value="2008">2008</option>\n<option value="2009">2009</option>\n}
     expected << "</select>\n"
 
@@ -2199,7 +2199,7 @@ class DateHelperTest < ActionView::TestCase
     @post = Post.new
     @post.written_on = Date.new(2004, 6, 15)
 
-    expected = %{<select id="post_written_on_1i" name="post[written_on(1i)]">\n}
+    expected = %{<select id="post_written_on_1i" name="post[written_on(1i)]">\n}.dup
     expected << %{<option value="1999">1999</option>\n<option value="2000">2000</option>\n<option value="2001">2001</option>\n<option value="2002">2002</option>\n<option value="2003">2003</option>\n<option value="2004" selected="selected">2004</option>\n<option value="2005">2005</option>\n<option value="2006">2006</option>\n<option value="2007">2007</option>\n<option value="2008">2008</option>\n<option value="2009">2009</option>\n}
     expected << "</select>\n"
 
@@ -2223,7 +2223,7 @@ class DateHelperTest < ActionView::TestCase
     @post = Post.new
     @post.written_on = Date.new(2004, 6, 15)
 
-    expected = %{<select id="post_written_on_3i" name="post[written_on(3i)]">\n}
+    expected = %{<select id="post_written_on_3i" name="post[written_on(3i)]">\n}.dup
     expected << %{<option value="1">1</option>\n<option value="2">2</option>\n<option value="3">3</option>\n<option value="4">4</option>\n<option value="5">5</option>\n<option value="6">6</option>\n<option value="7">7</option>\n<option value="8">8</option>\n<option value="9">9</option>\n<option value="10">10</option>\n<option value="11">11</option>\n<option value="12">12</option>\n<option value="13">13</option>\n<option value="14">14</option>\n<option value="15" selected="selected">15</option>\n<option value="16">16</option>\n<option value="17">17</option>\n<option value="18">18</option>\n<option value="19">19</option>\n<option value="20">20</option>\n<option value="21">21</option>\n<option value="22">22</option>\n<option value="23">23</option>\n<option value="24">24</option>\n<option value="25">25</option>\n<option value="26">26</option>\n<option value="27">27</option>\n<option value="28">28</option>\n<option value="29">29</option>\n<option value="30">30</option>\n<option value="31">31</option>\n}
     expected << "</select>\n"
 
@@ -2246,7 +2246,7 @@ class DateHelperTest < ActionView::TestCase
     @post = Post.new
     @post.written_on = Date.new(2004, 6, 15)
 
-    expected = %{<select id="post_written_on_3i" name="post[written_on(3i)]">\n}
+    expected = %{<select id="post_written_on_3i" name="post[written_on(3i)]">\n}.dup
     expected << %{<option value="1">1</option>\n<option value="2">2</option>\n<option value="3">3</option>\n<option value="4">4</option>\n<option value="5">5</option>\n<option value="6">6</option>\n<option value="7">7</option>\n<option value="8">8</option>\n<option value="9">9</option>\n<option value="10">10</option>\n<option value="11">11</option>\n<option value="12">12</option>\n<option value="13">13</option>\n<option value="14">14</option>\n<option value="15" selected="selected">15</option>\n<option value="16">16</option>\n<option value="17">17</option>\n<option value="18">18</option>\n<option value="19">19</option>\n<option value="20">20</option>\n<option value="21">21</option>\n<option value="22">22</option>\n<option value="23">23</option>\n<option value="24">24</option>\n<option value="25">25</option>\n<option value="26">26</option>\n<option value="27">27</option>\n<option value="28">28</option>\n<option value="29">29</option>\n<option value="30">30</option>\n<option value="31">31</option>\n}
     expected << "</select>\n"
 
@@ -2264,7 +2264,7 @@ class DateHelperTest < ActionView::TestCase
     @post = Post.new
     @post.written_on = Date.new(2004, 6, 15)
 
-    expected = %{<select id="post_written_on_1i" name="post[written_on(1i)]">\n}
+    expected = %{<select id="post_written_on_1i" name="post[written_on(1i)]">\n}.dup
     expected << %{<option value="">Year</option>\n<option value="1999">1999</option>\n<option value="2000">2000</option>\n<option value="2001">2001</option>\n<option value="2002">2002</option>\n<option value="2003">2003</option>\n<option value="2004" selected="selected">2004</option>\n<option value="2005">2005</option>\n<option value="2006">2006</option>\n<option value="2007">2007</option>\n<option value="2008">2008</option>\n<option value="2009">2009</option>\n}
     expected << "</select>\n"
 
@@ -2284,7 +2284,7 @@ class DateHelperTest < ActionView::TestCase
     @post = Post.new
     @post.written_on = Date.new(2004, 6, 15)
 
-    expected = %{<select id="post_written_on_1i" name="post[written_on(1i)]">\n}
+    expected = %{<select id="post_written_on_1i" name="post[written_on(1i)]">\n}.dup
     expected << %{<option value="">Choose year</option>\n<option value="1999">1999</option>\n<option value="2000">2000</option>\n<option value="2001">2001</option>\n<option value="2002">2002</option>\n<option value="2003">2003</option>\n<option value="2004" selected="selected">2004</option>\n<option value="2005">2005</option>\n<option value="2006">2006</option>\n<option value="2007">2007</option>\n<option value="2008">2008</option>\n<option value="2009">2009</option>\n}
     expected << "</select>\n"
 
@@ -2304,7 +2304,7 @@ class DateHelperTest < ActionView::TestCase
     @post = Post.new
     @post.written_on = Date.new(2004, 6, 15)
 
-    expected = %{<select id="post_written_on_1i" name="post[written_on(1i)]" class="year">\n}
+    expected = %{<select id="post_written_on_1i" name="post[written_on(1i)]" class="year">\n}.dup
     expected << %{<option value="1999">1999</option>\n<option value="2000">2000</option>\n<option value="2001">2001</option>\n<option value="2002">2002</option>\n<option value="2003">2003</option>\n<option value="2004" selected="selected">2004</option>\n<option value="2005">2005</option>\n<option value="2006">2006</option>\n<option value="2007">2007</option>\n<option value="2008">2008</option>\n<option value="2009">2009</option>\n}
     expected << "</select>\n"
 
@@ -2324,7 +2324,7 @@ class DateHelperTest < ActionView::TestCase
     @post = Post.new
     @post.written_on = Date.new(2004, 6, 15)
 
-    expected = %{<select id="post_written_on_1i" name="post[written_on(1i)]" class="my-year">\n}
+    expected = %{<select id="post_written_on_1i" name="post[written_on(1i)]" class="my-year">\n}.dup
     expected << %{<option value="1999">1999</option>\n<option value="2000">2000</option>\n<option value="2001">2001</option>\n<option value="2002">2002</option>\n<option value="2003">2003</option>\n<option value="2004" selected="selected">2004</option>\n<option value="2005">2005</option>\n<option value="2006">2006</option>\n<option value="2007">2007</option>\n<option value="2008">2008</option>\n<option value="2009">2009</option>\n}
     expected << "</select>\n"
 
@@ -2344,7 +2344,7 @@ class DateHelperTest < ActionView::TestCase
     @post = Post.new
     @post.written_on = Time.local(2004, 6, 15, 15, 16, 35)
 
-    expected = %{<input type="hidden" id="post_written_on_1i" name="post[written_on(1i)]" value="2004" />\n}
+    expected = %{<input type="hidden" id="post_written_on_1i" name="post[written_on(1i)]" value="2004" />\n}.dup
     expected << %{<input type="hidden" id="post_written_on_2i" name="post[written_on(2i)]" value="6" />\n}
     expected << %{<input type="hidden" id="post_written_on_3i" name="post[written_on(3i)]" value="15" />\n}
 
@@ -2363,7 +2363,7 @@ class DateHelperTest < ActionView::TestCase
     @post = Post.new
     @post.written_on = Time.local(2004, 6, 15, 15, 16, 35)
 
-    expected = %{<input type="hidden" id="post_written_on_1i" name="post[written_on(1i)]" value="2004" />\n}
+    expected = %{<input type="hidden" id="post_written_on_1i" name="post[written_on(1i)]" value="2004" />\n}.dup
     expected << %{<input type="hidden" id="post_written_on_2i" name="post[written_on(2i)]" value="6" />\n}
     expected << %{<input type="hidden" id="post_written_on_3i" name="post[written_on(3i)]" value="15" />\n}
 
@@ -2382,7 +2382,7 @@ class DateHelperTest < ActionView::TestCase
     @post = Post.new
     @post.written_on = Time.local(2004, 6, 15, 15, 16, 35)
 
-    expected = %{<input type="hidden" id="post_written_on_1i" name="post[written_on(1i)]" value="1" />\n}
+    expected = %{<input type="hidden" id="post_written_on_1i" name="post[written_on(1i)]" value="1" />\n}.dup
     expected << %{<input type="hidden" id="post_written_on_2i" name="post[written_on(2i)]" value="1" />\n}
     expected << %{<input type="hidden" id="post_written_on_3i" name="post[written_on(3i)]" value="1" />\n}
 
@@ -2401,7 +2401,7 @@ class DateHelperTest < ActionView::TestCase
     @post = Post.new
     @post.written_on = Time.local(2004, 6, 15, 15, 16, 35)
 
-    expected = %(<select id="post_written_on_4i" name="post[written_on(4i)]">\n)
+    expected = %(<select id="post_written_on_4i" name="post[written_on(4i)]">\n).dup
     0.upto(23) { |i| expected << %(<option value="#{sprintf("%02d", i)}"#{' selected="selected"' if i == 15}>#{sprintf("%02d", i)}</option>\n) }
     expected << "</select>\n"
     expected << " : "
@@ -2416,7 +2416,7 @@ class DateHelperTest < ActionView::TestCase
     @post = Post.new
     @post.written_on = Time.local(2004, 6, 15, 15, 16, 35)
 
-    expected = %{<input type="hidden" id="post_written_on_1i" name="post[written_on(1i)]" value="2004" />\n}
+    expected = %{<input type="hidden" id="post_written_on_1i" name="post[written_on(1i)]" value="2004" />\n}.dup
     expected << %{<input type="hidden" id="post_written_on_2i" name="post[written_on(2i)]" value="6" />\n}
     expected << %{<input type="hidden" id="post_written_on_3i" name="post[written_on(3i)]" value="15" />\n}
 
@@ -2439,7 +2439,7 @@ class DateHelperTest < ActionView::TestCase
     @post = Post.new
     @post.written_on = Time.local(2004, 6, 15, 15, 16, 35)
 
-    expected = %{<input type="hidden" id="post_written_on_1i" name="post[written_on(1i)]" value="2004" />\n}
+    expected = %{<input type="hidden" id="post_written_on_1i" name="post[written_on(1i)]" value="2004" />\n}.dup
     expected << %{<input type="hidden" id="post_written_on_2i" name="post[written_on(2i)]" value="6" />\n}
     expected << %{<input type="hidden" id="post_written_on_3i" name="post[written_on(3i)]" value="15" />\n}
 
@@ -2462,7 +2462,7 @@ class DateHelperTest < ActionView::TestCase
       concat f.time_select(:written_on, {}, class: "selector")
     end
 
-    expected = %{<input type="hidden" id="post_written_on_1i" name="post[written_on(1i)]" value="2004" />\n}
+    expected = %{<input type="hidden" id="post_written_on_1i" name="post[written_on(1i)]" value="2004" />\n}.dup
     expected << %{<input type="hidden" id="post_written_on_2i" name="post[written_on(2i)]" value="6" />\n}
     expected << %{<input type="hidden" id="post_written_on_3i" name="post[written_on(3i)]" value="15" />\n}
 
@@ -2481,7 +2481,7 @@ class DateHelperTest < ActionView::TestCase
     @post = Post.new
     @post.written_on = Time.local(2004, 6, 15, 15, 16, 35)
 
-    expected = %{<input type="hidden" id="post_written_on_1i" name="post[written_on(1i)]" value="2004" />\n}
+    expected = %{<input type="hidden" id="post_written_on_1i" name="post[written_on(1i)]" value="2004" />\n}.dup
     expected << %{<input type="hidden" id="post_written_on_2i" name="post[written_on(2i)]" value="6" />\n}
     expected << %{<input type="hidden" id="post_written_on_3i" name="post[written_on(3i)]" value="15" />\n}
 
@@ -2508,7 +2508,7 @@ class DateHelperTest < ActionView::TestCase
     @post = Post.new
     @post.written_on = Time.local(2004, 6, 15, 15, 16, 35)
 
-    expected = %{<input type="hidden" id="post_written_on_1i" name="post[written_on(1i)]" value="2004" />\n}
+    expected = %{<input type="hidden" id="post_written_on_1i" name="post[written_on(1i)]" value="2004" />\n}.dup
     expected << %{<input type="hidden" id="post_written_on_2i" name="post[written_on(2i)]" value="6" />\n}
     expected << %{<input type="hidden" id="post_written_on_3i" name="post[written_on(3i)]" value="15" />\n}
 
@@ -2529,7 +2529,7 @@ class DateHelperTest < ActionView::TestCase
     @post = Post.new
     @post.written_on = Time.local(2004, 6, 15, 15, 16, 35)
 
-    expected = %{<input type="hidden" id="post_written_on_1i" name="post[written_on(1i)]" value="2004" />\n}
+    expected = %{<input type="hidden" id="post_written_on_1i" name="post[written_on(1i)]" value="2004" />\n}.dup
     expected << %{<input type="hidden" id="post_written_on_2i" name="post[written_on(2i)]" value="6" />\n}
     expected << %{<input type="hidden" id="post_written_on_3i" name="post[written_on(3i)]" value="15" />\n}
 
@@ -2550,7 +2550,7 @@ class DateHelperTest < ActionView::TestCase
     @post = Post.new
     @post.written_on = Time.local(2004, 6, 15, 15, 16, 35)
 
-    expected = %{<input type="hidden" id="post_written_on_1i" name="post[written_on(1i)]" value="2004" />\n}
+    expected = %{<input type="hidden" id="post_written_on_1i" name="post[written_on(1i)]" value="2004" />\n}.dup
     expected << %{<input type="hidden" id="post_written_on_2i" name="post[written_on(2i)]" value="6" />\n}
     expected << %{<input type="hidden" id="post_written_on_3i" name="post[written_on(3i)]" value="15" />\n}
 
@@ -2571,7 +2571,7 @@ class DateHelperTest < ActionView::TestCase
     @post = Post.new
     @post.written_on = Time.local(2004, 6, 15, 15, 16, 35)
 
-    expected = %{<input type="hidden" id="post_written_on_1i" name="post[written_on(1i)]" value="2004" />\n}
+    expected = %{<input type="hidden" id="post_written_on_1i" name="post[written_on(1i)]" value="2004" />\n}.dup
     expected << %{<input type="hidden" id="post_written_on_2i" name="post[written_on(2i)]" value="6" />\n}
     expected << %{<input type="hidden" id="post_written_on_3i" name="post[written_on(3i)]" value="15" />\n}
 
@@ -2592,7 +2592,7 @@ class DateHelperTest < ActionView::TestCase
     @post = Post.new
     @post.written_on = Time.local(2004, 6, 15, 15, 16, 35)
 
-    expected = %{<input type="hidden" id="post_written_on_1i" disabled="disabled" name="post[written_on(1i)]" value="2004" />\n}
+    expected = %{<input type="hidden" id="post_written_on_1i" disabled="disabled" name="post[written_on(1i)]" value="2004" />\n}.dup
     expected << %{<input type="hidden" id="post_written_on_2i" disabled="disabled" name="post[written_on(2i)]" value="6" />\n}
     expected << %{<input type="hidden" id="post_written_on_3i" disabled="disabled" name="post[written_on(3i)]" value="15" />\n}
 
@@ -2611,7 +2611,7 @@ class DateHelperTest < ActionView::TestCase
     @post = Post.new
     @post.updated_at = Time.local(2004, 6, 15, 16, 35)
 
-    expected = %{<select id="post_updated_at_1i" name="post[updated_at(1i)]">\n}
+    expected = %{<select id="post_updated_at_1i" name="post[updated_at(1i)]">\n}.dup
     expected << %{<option value="1999">1999</option>\n<option value="2000">2000</option>\n<option value="2001">2001</option>\n<option value="2002">2002</option>\n<option value="2003">2003</option>\n<option value="2004" selected="selected">2004</option>\n<option value="2005">2005</option>\n<option value="2006">2006</option>\n<option value="2007">2007</option>\n<option value="2008">2008</option>\n<option value="2009">2009</option>\n}
     expected << "</select>\n"
 
@@ -2640,7 +2640,7 @@ class DateHelperTest < ActionView::TestCase
     @post = Post.new
     @post.updated_at = Time.local(2004, 6, 15, 16, 35)
 
-    expected = %{<select id="post_updated_at_1i" name="post[updated_at(1i)]">\n}
+    expected = %{<select id="post_updated_at_1i" name="post[updated_at(1i)]">\n}.dup
     expected << %{<option value="1999">1999</option>\n<option value="2000">2000</option>\n<option value="2001">2001</option>\n<option value="2002">2002</option>\n<option value="2003">2003</option>\n<option value="2004" selected="selected">2004</option>\n<option value="2005">2005</option>\n<option value="2006">2006</option>\n<option value="2007">2007</option>\n<option value="2008">2008</option>\n<option value="2009">2009</option>\n}
     expected << "</select>\n"
 
@@ -2706,7 +2706,7 @@ class DateHelperTest < ActionView::TestCase
 
     @post = Post.new
 
-    expected = %{<select id="post_updated_at_1i" name="post[updated_at(1i)]">\n}
+    expected = %{<select id="post_updated_at_1i" name="post[updated_at(1i)]">\n}.dup
     expected << %{<option value="1999">1999</option>\n<option value="2000">2000</option>\n<option value="2001">2001</option>\n<option value="2002">2002</option>\n<option value="2003">2003</option>\n<option value="2004" selected="selected">2004</option>\n<option value="2005">2005</option>\n<option value="2006">2006</option>\n<option value="2007">2007</option>\n<option value="2008">2008</option>\n<option value="2009">2009</option>\n}
     expected << "</select>\n"
 
@@ -2741,7 +2741,7 @@ class DateHelperTest < ActionView::TestCase
       concat f.datetime_select(:updated_at, {}, class: "selector")
     end
 
-    expected = %{<select id="post_updated_at_1i" name="post[updated_at(1i)]" class="selector">\n<option value="1999">1999</option>\n<option value="2000">2000</option>\n<option value="2001">2001</option>\n<option value="2002">2002</option>\n<option value="2003">2003</option>\n<option selected="selected" value="2004">2004</option>\n<option value="2005">2005</option>\n<option value="2006">2006</option>\n<option value="2007">2007</option>\n<option value="2008">2008</option>\n<option value="2009">2009</option>\n</select>\n}
+    expected = %{<select id="post_updated_at_1i" name="post[updated_at(1i)]" class="selector">\n<option value="1999">1999</option>\n<option value="2000">2000</option>\n<option value="2001">2001</option>\n<option value="2002">2002</option>\n<option value="2003">2003</option>\n<option selected="selected" value="2004">2004</option>\n<option value="2005">2005</option>\n<option value="2006">2006</option>\n<option value="2007">2007</option>\n<option value="2008">2008</option>\n<option value="2009">2009</option>\n</select>\n}.dup
     expected << %{<select id="post_updated_at_2i" name="post[updated_at(2i)]" class="selector">\n<option value="1">January</option>\n<option value="2">February</option>\n<option value="3">March</option>\n<option value="4">April</option>\n<option value="5">May</option>\n<option selected="selected" value="6">June</option>\n<option value="7">July</option>\n<option value="8">August</option>\n<option value="9">September</option>\n<option value="10">October</option>\n<option value="11">November</option>\n<option value="12">December</option>\n</select>\n}
     expected << %{<select id="post_updated_at_3i" name="post[updated_at(3i)]" class="selector">\n<option value="1">1</option>\n<option value="2">2</option>\n<option value="3">3</option>\n<option value="4">4</option>\n<option value="5">5</option>\n<option value="6">6</option>\n<option value="7">7</option>\n<option value="8">8</option>\n<option value="9">9</option>\n<option value="10">10</option>\n<option value="11">11</option>\n<option value="12">12</option>\n<option value="13">13</option>\n<option value="14">14</option>\n<option selected="selected" value="15">15</option>\n<option value="16">16</option>\n<option value="17">17</option>\n<option value="18">18</option>\n<option value="19">19</option>\n<option value="20">20</option>\n<option value="21">21</option>\n<option value="22">22</option>\n<option value="23">23</option>\n<option value="24">24</option>\n<option value="25">25</option>\n<option value="26">26</option>\n<option value="27">27</option>\n<option value="28">28</option>\n<option value="29">29</option>\n<option value="30">30</option>\n<option value="31">31</option>\n</select>\n}
     expected << %{ &mdash; <select id="post_updated_at_4i" name="post[updated_at(4i)]" class="selector">\n<option value="00">00</option>\n<option value="01">01</option>\n<option value="02">02</option>\n<option value="03">03</option>\n<option value="04">04</option>\n<option value="05">05</option>\n<option value="06">06</option>\n<option value="07">07</option>\n<option value="08">08</option>\n<option value="09">09</option>\n<option value="10">10</option>\n<option value="11">11</option>\n<option value="12">12</option>\n<option value="13">13</option>\n<option value="14">14</option>\n<option value="15">15</option>\n<option selected="selected" value="16">16</option>\n<option value="17">17</option>\n<option value="18">18</option>\n<option value="19">19</option>\n<option value="20">20</option>\n<option value="21">21</option>\n<option value="22">22</option>\n<option value="23">23</option>\n</select>\n}
@@ -2754,7 +2754,7 @@ class DateHelperTest < ActionView::TestCase
     @post = Post.new
     @post.updated_at = Time.local(2004, 6, 15, 15, 16, 35)
 
-    expected = %{<select id="post_updated_at_1i" name="post[updated_at(1i)]">\n}
+    expected = %{<select id="post_updated_at_1i" name="post[updated_at(1i)]">\n}.dup
     expected << %{<option value="1999">1999</option>\n<option value="2000">2000</option>\n<option value="2001">2001</option>\n<option value="2002">2002</option>\n<option value="2003">2003</option>\n<option value="2004" selected="selected">2004</option>\n<option value="2005">2005</option>\n<option value="2006">2006</option>\n<option value="2007">2007</option>\n<option value="2008">2008</option>\n<option value="2009">2009</option>\n}
     expected << "</select>\n"
 
@@ -2807,7 +2807,7 @@ class DateHelperTest < ActionView::TestCase
     @post = Post.new
     @post.updated_at = nil
 
-    expected = %{<select id="post_updated_at_1i" name="post[updated_at(1i)]">\n}
+    expected = %{<select id="post_updated_at_1i" name="post[updated_at(1i)]">\n}.dup
     expected << %{<option value="">Year</option>\n<option value="1999">1999</option>\n<option value="2000">2000</option>\n<option value="2001">2001</option>\n<option value="2002">2002</option>\n<option value="2003">2003</option>\n<option value="2004">2004</option>\n<option value="2005">2005</option>\n<option value="2006">2006</option>\n<option value="2007">2007</option>\n<option value="2008">2008</option>\n<option value="2009">2009</option>\n}
     expected << "</select>\n"
 
@@ -2836,7 +2836,7 @@ class DateHelperTest < ActionView::TestCase
     @post = Post.new
     @post.updated_at = nil
 
-    expected = %{<select id="post_updated_at_1i" name="post[updated_at(1i)]">\n}
+    expected = %{<select id="post_updated_at_1i" name="post[updated_at(1i)]">\n}.dup
     expected << %{<option value="">Choose year</option>\n<option value="1999">1999</option>\n<option value="2000">2000</option>\n<option value="2001">2001</option>\n<option value="2002">2002</option>\n<option value="2003">2003</option>\n<option value="2004">2004</option>\n<option value="2005">2005</option>\n<option value="2006">2006</option>\n<option value="2007">2007</option>\n<option value="2008">2008</option>\n<option value="2009">2009</option>\n}
     expected << "</select>\n"
 
@@ -2865,7 +2865,7 @@ class DateHelperTest < ActionView::TestCase
     @post = Post.new
     @post.written_on = Time.local(2004, 6, 15, 15, 16, 35)
 
-    expected = %{<select id="post_written_on_1i" name="post[written_on(1i)]" class="year">\n}
+    expected = %{<select id="post_written_on_1i" name="post[written_on(1i)]" class="year">\n}.dup
     expected << %{<option value="1999">1999</option>\n<option value="2000">2000</option>\n<option value="2001">2001</option>\n<option value="2002">2002</option>\n<option value="2003">2003</option>\n<option value="2004" selected="selected">2004</option>\n<option value="2005">2005</option>\n<option value="2006">2006</option>\n<option value="2007">2007</option>\n<option value="2008">2008</option>\n<option value="2009">2009</option>\n}
     expected << "</select>\n"
 
@@ -2894,7 +2894,7 @@ class DateHelperTest < ActionView::TestCase
     @post = Post.new
     @post.written_on = Time.local(2004, 6, 15, 15, 16, 35)
 
-    expected = %{<select id="post_written_on_1i" name="post[written_on(1i)]" class="my-year">\n}
+    expected = %{<select id="post_written_on_1i" name="post[written_on(1i)]" class="my-year">\n}.dup
     expected << %{<option value="1999">1999</option>\n<option value="2000">2000</option>\n<option value="2001">2001</option>\n<option value="2002">2002</option>\n<option value="2003">2003</option>\n<option value="2004" selected="selected">2004</option>\n<option value="2005">2005</option>\n<option value="2006">2006</option>\n<option value="2007">2007</option>\n<option value="2008">2008</option>\n<option value="2009">2009</option>\n}
     expected << "</select>\n"
 
@@ -2920,7 +2920,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_date_select_with_zero_value_and_no_start_year
-    expected = %(<select id="date_first_year" name="date[first][year]">\n)
+    expected = %(<select id="date_first_year" name="date[first][year]">\n).dup
     (Date.today.year - 5).upto(Date.today.year + 1) { |y| expected << %(<option value="#{y}">#{y}</option>\n) }
     expected << "</select>\n"
 
@@ -2936,7 +2936,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_date_select_with_zero_value_and_no_end_year
-    expected =  %(<select id="date_first_year" name="date[first][year]">\n)
+    expected =  %(<select id="date_first_year" name="date[first][year]">\n).dup
     last_year = Time.now.year + 5
     2003.upto(last_year) { |y| expected << %(<option value="#{y}">#{y}</option>\n) }
     expected << "</select>\n"
@@ -2953,7 +2953,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_date_select_with_zero_value_and_no_start_and_end_year
-    expected = %(<select id="date_first_year" name="date[first][year]">\n)
+    expected = %(<select id="date_first_year" name="date[first][year]">\n).dup
     (Date.today.year - 5).upto(Date.today.year + 5) { |y| expected << %(<option value="#{y}">#{y}</option>\n) }
     expected << "</select>\n"
 
@@ -2969,7 +2969,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_date_select_with_nil_value_and_no_start_and_end_year
-    expected = %(<select id="date_first_year" name="date[first][year]">\n)
+    expected = %(<select id="date_first_year" name="date[first][year]">\n).dup
     (Date.today.year - 5).upto(Date.today.year + 5) { |y| expected << %(<option value="#{y}">#{y}</option>\n) }
     expected << "</select>\n"
 
@@ -2985,7 +2985,7 @@ class DateHelperTest < ActionView::TestCase
   end
 
   def test_datetime_select_with_nil_value_and_no_start_and_end_year
-    expected = %(<select id="date_first_year" name="date[first][year]">\n)
+    expected = %(<select id="date_first_year" name="date[first][year]">\n).dup
     (Date.today.year - 5).upto(Date.today.year + 5) { |y| expected << %(<option value="#{y}">#{y}</option>\n) }
     expected << "</select>\n"
 
@@ -3017,7 +3017,7 @@ class DateHelperTest < ActionView::TestCase
     @post.updated_at = Time.local(2004, 6, 15, 16, 35)
     id = 456
 
-    expected = %{<select id="post_456_updated_at_1i" name="post[#{id}][updated_at(1i)]">\n}
+    expected = %{<select id="post_456_updated_at_1i" name="post[#{id}][updated_at(1i)]">\n}.dup
     expected << %{<option value="1999">1999</option>\n<option value="2000">2000</option>\n<option value="2001">2001</option>\n<option value="2002">2002</option>\n<option value="2003">2003</option>\n<option value="2004" selected="selected">2004</option>\n<option value="2005">2005</option>\n<option value="2006">2006</option>\n<option value="2007">2007</option>\n<option value="2008">2008</option>\n<option value="2009">2009</option>\n}
     expected << "</select>\n"
 
@@ -3051,7 +3051,7 @@ class DateHelperTest < ActionView::TestCase
       concat f.datetime_select(:updated_at)
     end
 
-    expected = %{<select id="post_456_updated_at_1i" name="post[#{id}][updated_at(1i)]">\n}
+    expected = %{<select id="post_456_updated_at_1i" name="post[#{id}][updated_at(1i)]">\n}.dup
     expected << %{<option value="1999">1999</option>\n<option value="2000">2000</option>\n<option value="2001">2001</option>\n<option value="2002">2002</option>\n<option value="2003">2003</option>\n<option value="2004" selected="selected">2004</option>\n<option value="2005">2005</option>\n<option value="2006">2006</option>\n<option value="2007">2007</option>\n<option value="2008">2008</option>\n<option value="2009">2009</option>\n}
     expected << "</select>\n"
 
@@ -3081,7 +3081,7 @@ class DateHelperTest < ActionView::TestCase
     @post.updated_at = Time.local(2004, 6, 15, 16, 35)
     id = @post.id
 
-    expected = %{<select id="post_123_updated_at_1i" name="post[#{id}][updated_at(1i)]">\n}
+    expected = %{<select id="post_123_updated_at_1i" name="post[#{id}][updated_at(1i)]">\n}.dup
     expected << %{<option value="1999">1999</option>\n<option value="2000">2000</option>\n<option value="2001">2001</option>\n<option value="2002">2002</option>\n<option value="2003">2003</option>\n<option value="2004" selected="selected">2004</option>\n<option value="2005">2005</option>\n<option value="2006">2006</option>\n<option value="2007">2007</option>\n<option value="2008">2008</option>\n<option value="2009">2009</option>\n}
     expected << "</select>\n"
 
@@ -3110,7 +3110,7 @@ class DateHelperTest < ActionView::TestCase
     @post = Post.new
     @post.updated_at = Time.local(2004, 6, 15, 15, 16, 35)
 
-    expected = %{<select id="post_updated_at_1i" name="post[updated_at(1i)]">\n}
+    expected = %{<select id="post_updated_at_1i" name="post[updated_at(1i)]">\n}.dup
     1999.upto(2009) { |i| expected << %(<option value="#{i}"#{' selected="selected"' if i == 2004}>#{i}</option>\n) }
     expected << "</select>\n"
     expected << %{<select id="post_updated_at_2i" name="post[updated_at(2i)]">\n}
@@ -3141,7 +3141,7 @@ class DateHelperTest < ActionView::TestCase
     @post = Post.new
     @post.updated_at = Time.local(2004, 6, 15, 15, 16, 35)
 
-    expected = %{<input type="hidden" id="post_updated_at_1i" name="post[updated_at(1i)]" value="2004" />\n}
+    expected = %{<input type="hidden" id="post_updated_at_1i" name="post[updated_at(1i)]" value="2004" />\n}.dup
     expected << %{<select id="post_updated_at_2i" name="post[updated_at(2i)]">\n}
     1.upto(12) { |i| expected << %(<option value="#{i}"#{' selected="selected"' if i == 6}>#{Date::MONTHNAMES[i]}</option>\n) }
     expected << "</select>\n"
@@ -3166,7 +3166,7 @@ class DateHelperTest < ActionView::TestCase
     @post = Post.new
     @post.updated_at = Time.local(2004, 6, 15, 15, 16, 35)
 
-    expected = %{<select id="post_updated_at_1i" name="post[updated_at(1i)]">\n}
+    expected = %{<select id="post_updated_at_1i" name="post[updated_at(1i)]">\n}.dup
     1999.upto(2009) { |i| expected << %(<option value="#{i}"#{' selected="selected"' if i == 2004}>#{i}</option>\n) }
     expected << "</select>\n"
     expected << %{<input type="hidden" id="post_updated_at_2i" name="post[updated_at(2i)]" value="6" />\n}
@@ -3189,7 +3189,7 @@ class DateHelperTest < ActionView::TestCase
     @post = Post.new
     @post.updated_at = Time.local(2004, 6, 15, 15, 16, 35)
 
-    expected = %{<input type="hidden" id="post_updated_at_1i" name="post[updated_at(1i)]" value="2004" />\n}
+    expected = %{<input type="hidden" id="post_updated_at_1i" name="post[updated_at(1i)]" value="2004" />\n}.dup
     expected << %{<input type="hidden" id="post_updated_at_2i" name="post[updated_at(2i)]" value="6" />\n}
     expected << %{<input type="hidden" id="post_updated_at_3i" name="post[updated_at(3i)]" value="1" />\n}
 
@@ -3208,7 +3208,7 @@ class DateHelperTest < ActionView::TestCase
     @post = Post.new
     @post.updated_at = Time.local(2004, 6, 15, 15, 16, 35)
 
-    expected = %{<input type="hidden" id="post_updated_at_1i" disabled="disabled" name="post[updated_at(1i)]" value="2004" />\n}
+    expected = %{<input type="hidden" id="post_updated_at_1i" disabled="disabled" name="post[updated_at(1i)]" value="2004" />\n}.dup
     expected << %{<input type="hidden" id="post_updated_at_2i" disabled="disabled" name="post[updated_at(2i)]" value="6" />\n}
     expected << %{<input type="hidden" id="post_updated_at_3i" disabled="disabled" name="post[updated_at(3i)]" value="1" />\n}
 
@@ -3227,7 +3227,7 @@ class DateHelperTest < ActionView::TestCase
     @post = Post.new
     @post.updated_at = Time.local(2004, 6, 15, 15, 16, 35)
 
-    expected = %{<select id="post_updated_at_1i" name="post[updated_at(1i)]">\n}
+    expected = %{<select id="post_updated_at_1i" name="post[updated_at(1i)]">\n}.dup
     1999.upto(2009) { |i| expected << %(<option value="#{i}"#{' selected="selected"' if i == 2004}>#{i}</option>\n) }
     expected << "</select>\n"
     expected << %{<select id="post_updated_at_2i" name="post[updated_at(2i)]">\n}
@@ -3244,7 +3244,7 @@ class DateHelperTest < ActionView::TestCase
     @post = Post.new
     @post.updated_at = Time.local(2004, 6, 15, 15, 16, 35)
 
-    expected = %{<select id="post_updated_at_1i" name="post[updated_at(1i)]">\n}
+    expected = %{<select id="post_updated_at_1i" name="post[updated_at(1i)]">\n}.dup
     1999.upto(2009) { |i| expected << %(<option value="#{i}"#{' selected="selected"' if i == 2004}>#{i}</option>\n) }
     expected << "</select>\n"
     expected << %{<select id="post_updated_at_2i" name="post[updated_at(2i)]">\n}
@@ -3268,7 +3268,7 @@ class DateHelperTest < ActionView::TestCase
     @post = Post.new
     @post.updated_at = Time.local(2004, 6, 15, 15, 16, 35)
 
-    expected = %{<select id="post_updated_at_1i" disabled="disabled" name="post[updated_at(1i)]">\n}
+    expected = %{<select id="post_updated_at_1i" disabled="disabled" name="post[updated_at(1i)]">\n}.dup
     1999.upto(2009) { |i| expected << %(<option value="#{i}"#{' selected="selected"' if i == 2004}>#{i}</option>\n) }
     expected << "</select>\n"
     expected << %{<select id="post_updated_at_2i" disabled="disabled" name="post[updated_at(2i)]">\n}
@@ -3292,7 +3292,7 @@ class DateHelperTest < ActionView::TestCase
     @post = Post.new
     @post.updated_at = Time.local(2004, 6, 15, 15, 16, 35)
 
-    expected = %{<select id="post_updated_at_3i" name="post[updated_at(3i)]">\n}
+    expected = %{<select id="post_updated_at_3i" name="post[updated_at(3i)]">\n}.dup
     1.upto(31) { |i| expected << %(<option value="#{i}"#{' selected="selected"' if i == 15}>#{i}</option>\n) }
     expected << "</select>\n"
     expected << %{<select id="post_updated_at_2i" name="post[updated_at(2i)]">\n}
@@ -3319,7 +3319,7 @@ class DateHelperTest < ActionView::TestCase
     @post = Post.new
     @post.updated_at = Time.local(2004, 6, 15, 15, 16, 35)
 
-    expected = %{<input type="hidden" id="post_updated_at_1i" name="post[updated_at(1i)]" value="2004" />\n}
+    expected = %{<input type="hidden" id="post_updated_at_1i" name="post[updated_at(1i)]" value="2004" />\n}.dup
     expected << %{<select id="post_updated_at_3i" name="post[updated_at(3i)]">\n}
     1.upto(31) { |i| expected << %(<option value="#{i}"#{' selected="selected"' if i == 15}>#{i}</option>\n) }
     expected << "</select>\n"
@@ -3344,7 +3344,7 @@ class DateHelperTest < ActionView::TestCase
     @post = Post.new
     @post.updated_at = nil
 
-    expected = %{<select id="post_updated_at_1i" name="post[updated_at(1i)]">\n}
+    expected = %{<select id="post_updated_at_1i" name="post[updated_at(1i)]">\n}.dup
     2001.upto(2011) { |i| expected << %(<option value="#{i}"#{' selected="selected"' if i == 2006}>#{i}</option>\n) }
     expected << "</select>\n"
     expected << %{<select id="post_updated_at_2i" name="post[updated_at(2i)]">\n}
@@ -3371,7 +3371,7 @@ class DateHelperTest < ActionView::TestCase
     @post = Post.new
     @post.updated_at = nil
 
-    expected = %{<select id="post_updated_at_1i" name="post[updated_at(1i)]">\n}
+    expected = %{<select id="post_updated_at_1i" name="post[updated_at(1i)]">\n}.dup
     expected << %(<option value=""></option>\n)
     (Time.now.year - 5).upto(Time.now.year + 5) { |i| expected << %(<option value="#{i}">#{i}</option>\n) }
     expected << "</select>\n"
@@ -3391,7 +3391,7 @@ class DateHelperTest < ActionView::TestCase
     @post = Post.new
     @post.updated_at = nil
 
-    expected = %{<select id="post_updated_at_1i" name="post[updated_at(1i)]">\n}
+    expected = %{<select id="post_updated_at_1i" name="post[updated_at(1i)]">\n}.dup
     (Time.now.year - 5).upto(Time.now.year + 5) { |i| expected << %(<option value="#{i}"#{' selected="selected"' if i == Time.now.year}>#{i}</option>\n) }
     expected << "</select>\n"
     expected << %{<select id="post_updated_at_2i" name="post[updated_at(2i)]">\n}
@@ -3418,7 +3418,7 @@ class DateHelperTest < ActionView::TestCase
     @post = Post.new
     @post.updated_at = Time.local(2004, 6, 15, 16, 35)
 
-    expected = %{<select id="post_updated_at_1i" name="post[updated_at(1i)]" class="selector">\n}
+    expected = %{<select id="post_updated_at_1i" name="post[updated_at(1i)]" class="selector">\n}.dup
     expected << %{<option value="1999">1999</option>\n<option value="2000">2000</option>\n<option value="2001">2001</option>\n<option value="2002">2002</option>\n<option value="2003">2003</option>\n<option value="2004" selected="selected">2004</option>\n<option value="2005">2005</option>\n<option value="2006">2006</option>\n<option value="2007">2007</option>\n<option value="2008">2008</option>\n<option value="2009">2009</option>\n}
     expected << "</select>\n"
 
diff --git a/actionview/test/template/form_helper/form_with_test.rb b/actionview/test/template/form_helper/form_with_test.rb
index ecdd5ce672..df81315b9c 100644
--- a/actionview/test/template/form_helper/form_with_test.rb
+++ b/actionview/test/template/form_helper/form_with_test.rb
@@ -16,7 +16,7 @@ class FormWithActsLikeFormTagTest < FormWithTest
     method = options[:method]
     skip_enforcing_utf8 = options.fetch(:skip_enforcing_utf8, false)
 
-    "".tap do |txt|
+    "".dup.tap do |txt|
       unless skip_enforcing_utf8
         txt << %{<input name="utf8" type="hidden" value="&#x2713;" />}
       end
@@ -32,7 +32,7 @@ class FormWithActsLikeFormTagTest < FormWithTest
 
     method = method.to_s == "get" ? "get" : "post"
 
-    txt =  %{<form accept-charset="UTF-8" action="#{action}"}
+    txt =  %{<form accept-charset="UTF-8" action="#{action}"}.dup
     txt << %{ enctype="multipart/form-data"} if enctype
     txt << %{ data-remote="true"} unless local
     txt << %{ class="#{html_class}"} if html_class
@@ -2194,9 +2194,9 @@ class FormWithActsLikeFormForTest < FormWithTest
       method = options[:method]
 
       if options.fetch(:skip_enforcing_utf8, false)
-        txt = ""
+        txt = "".dup
       else
-        txt = %{<input name="utf8" type="hidden" value="&#x2713;" />}
+        txt = %{<input name="utf8" type="hidden" value="&#x2713;" />}.dup
       end
 
       if method && !%w(get post).include?(method.to_s)
@@ -2207,7 +2207,7 @@ class FormWithActsLikeFormForTest < FormWithTest
     end
 
     def form_text(action = "/", id = nil, html_class = nil, local = nil, multipart = nil, method = nil)
-      txt =  %{<form accept-charset="UTF-8" action="#{action}"}
+      txt =  %{<form accept-charset="UTF-8" action="#{action}"}.dup
       txt << %{ enctype="multipart/form-data"} if multipart
       txt << %{ data-remote="true"} unless local
       txt << %{ class="#{html_class}"} if html_class
diff --git a/actionview/test/template/form_helper_test.rb b/actionview/test/template/form_helper_test.rb
index b3a180b28a..50dee1e999 100644
--- a/actionview/test/template/form_helper_test.rb
+++ b/actionview/test/template/form_helper_test.rb
@@ -3446,9 +3446,9 @@ class FormHelperTest < ActionView::TestCase
       method = options[:method]
 
       if options.fetch(:enforce_utf8, true)
-        txt = %{<input name="utf8" type="hidden" value="&#x2713;" />}
+        txt = %{<input name="utf8" type="hidden" value="&#x2713;" />}.dup
       else
-        txt = ""
+        txt = "".dup
       end
 
       if method && !%w(get post).include?(method.to_s)
@@ -3459,7 +3459,7 @@ class FormHelperTest < ActionView::TestCase
     end
 
     def form_text(action = "/", id = nil, html_class = nil, remote = nil, multipart = nil, method = nil)
-      txt =  %{<form accept-charset="UTF-8" action="#{action}"}
+      txt =  %{<form accept-charset="UTF-8" action="#{action}"}.dup
       txt << %{ enctype="multipart/form-data"} if multipart
       txt << %{ data-remote="true"} if remote
       txt << %{ class="#{html_class}"} if html_class
diff --git a/actionview/test/template/form_tag_helper_test.rb b/actionview/test/template/form_tag_helper_test.rb
index c13d0c32ae..7ac15db9fe 100644
--- a/actionview/test/template/form_tag_helper_test.rb
+++ b/actionview/test/template/form_tag_helper_test.rb
@@ -14,7 +14,7 @@ class FormTagHelperTest < ActionView::TestCase
     method = options[:method]
     enforce_utf8 = options.fetch(:enforce_utf8, true)
 
-    "".tap do |txt|
+    "".dup.tap do |txt|
       if enforce_utf8
         txt << %{<input name="utf8" type="hidden" value="&#x2713;" />}
       end
@@ -30,7 +30,7 @@ class FormTagHelperTest < ActionView::TestCase
 
     method = method.to_s == "get" ? "get" : "post"
 
-    txt =  %{<form accept-charset="UTF-8" action="#{action}"}
+    txt =  %{<form accept-charset="UTF-8" action="#{action}"}.dup
     txt << %{ enctype="multipart/form-data"} if enctype
     txt << %{ data-remote="true"} if remote
     txt << %{ class="#{html_class}"} if html_class
diff --git a/actionview/test/template/javascript_helper_test.rb b/actionview/test/template/javascript_helper_test.rb
index c7670b056b..67747a7a83 100644
--- a/actionview/test/template/javascript_helper_test.rb
+++ b/actionview/test/template/javascript_helper_test.rb
@@ -20,8 +20,8 @@ class JavaScriptHelperTest < ActionView::TestCase
     assert_equal %(This \\"thing\\" is really\\n netos\\'), escape_javascript(%(This "thing" is really\n netos'))
     assert_equal %(backslash\\\\test), escape_javascript(%(backslash\\test))
     assert_equal %(dont <\\/close> tags), escape_javascript(%(dont </close> tags))
-    assert_equal %(unicode &#x2028; newline), escape_javascript(%(unicode \342\200\250 newline).force_encoding(Encoding::UTF_8).encode!)
-    assert_equal %(unicode &#x2029; newline), escape_javascript(%(unicode \342\200\251 newline).force_encoding(Encoding::UTF_8).encode!)
+    assert_equal %(unicode &#x2028; newline), escape_javascript(%(unicode \342\200\250 newline).dup.force_encoding(Encoding::UTF_8).encode!)
+    assert_equal %(unicode &#x2029; newline), escape_javascript(%(unicode \342\200\251 newline).dup.force_encoding(Encoding::UTF_8).encode!)
 
     assert_equal %(dont <\\/close> tags), j(%(dont </close> tags))
   end
diff --git a/actionview/test/template/render_test.rb b/actionview/test/template/render_test.rb
index 9999607067..1fd8b4fe1a 100644
--- a/actionview/test/template/render_test.rb
+++ b/actionview/test/template/render_test.rb
@@ -439,7 +439,7 @@ module RenderTestCases
   end
 
   CustomHandler = lambda do |template|
-    "@output_buffer = ''\n" \
+    "@output_buffer = ''.dup\n" \
       "@output_buffer << 'source: #{template.source.inspect}'\n"
   end
 
@@ -583,7 +583,7 @@ module RenderTestCases
 
   def test_render_with_passing_couple_extensions_to_one_register_template_handler_function_call
     ActionView::Template.register_template_handler :foo1, :foo2, CustomHandler
-    assert_equal @view.render(inline: "Hello, World!", type: :foo1), @view.render(inline: "Hello, World!", type: :foo2)
+    assert_equal @view.render(inline: "Hello, World!".dup, type: :foo1), @view.render(inline: "Hello, World!".dup, type: :foo2)
   ensure
     ActionView::Template.unregister_template_handler :foo1, :foo2
   end
diff --git a/actionview/test/template/streaming_render_test.rb b/actionview/test/template/streaming_render_test.rb
index 6ce66a1275..41b9063417 100644
--- a/actionview/test/template/streaming_render_test.rb
+++ b/actionview/test/template/streaming_render_test.rb
@@ -17,7 +17,7 @@ class FiberedTest < ActiveSupport::TestCase
 
   def buffered_render(options)
     body = render_body(options)
-    string = ""
+    string = "".dup
     body.each do |piece|
       string << piece
     end
diff --git a/actionview/test/template/template_test.rb b/actionview/test/template/template_test.rb
index 9d31a98703..dd131f0246 100644
--- a/actionview/test/template/template_test.rb
+++ b/actionview/test/template/template_test.rb
@@ -53,7 +53,7 @@ class TestERBTemplate < ActiveSupport::TestCase
   end
 
   def new_template(body = "<%= hello %>", details = { format: :html })
-    ActionView::Template.new(body, "hello template", details.fetch(:handler) { ERBHandler }, { virtual_path: "hello" }.merge!(details))
+    ActionView::Template.new(body.dup, "hello template", details.fetch(:handler) { ERBHandler }, { virtual_path: "hello" }.merge!(details))
   end
 
   def render(locals = {})
diff --git a/actionview/test/template/text_helper_test.rb b/actionview/test/template/text_helper_test.rb
index 251c98230f..21ee4cc8e5 100644
--- a/actionview/test/template/text_helper_test.rb
+++ b/actionview/test/template/text_helper_test.rb
@@ -11,7 +11,7 @@ class TextHelperTest < ActionView::TestCase
   end
 
   def test_concat
-    self.output_buffer = "foo"
+    self.output_buffer = "foo".dup
     assert_equal "foobar", concat("bar")
     assert_equal "foobar", output_buffer
   end
@@ -104,8 +104,8 @@ class TextHelperTest < ActionView::TestCase
   end
 
   def test_truncate_multibyte
-    assert_equal "\354\225\204\353\246\254\353\236\221 \354\225\204\353\246\254 ...".force_encoding(Encoding::UTF_8),
-      truncate("\354\225\204\353\246\254\353\236\221 \354\225\204\353\246\254 \354\225\204\353\235\274\353\246\254\354\230\244".force_encoding(Encoding::UTF_8), length: 10)
+    assert_equal "\354\225\204\353\246\254\353\236\221 \354\225\204\353\246\254 ...".dup.force_encoding(Encoding::UTF_8),
+      truncate("\354\225\204\353\246\254\353\236\221 \354\225\204\353\246\254 \354\225\204\353\235\274\353\246\254\354\230\244".dup.force_encoding(Encoding::UTF_8), length: 10)
   end
 
   def test_truncate_does_not_modify_the_options_hash
@@ -325,7 +325,7 @@ class TextHelperTest < ActionView::TestCase
   end
 
   def test_excerpt_with_utf8
-    assert_equal("...\357\254\203ciency could not be...".force_encoding(Encoding::UTF_8), excerpt("That's why e\357\254\203ciency could not be helped".force_encoding(Encoding::UTF_8), "could", radius: 8))
+    assert_equal("...\357\254\203ciency could not be...".dup.force_encoding(Encoding::UTF_8), excerpt("That's why e\357\254\203ciency could not be helped".dup.force_encoding(Encoding::UTF_8), "could", radius: 8))
   end
 
   def test_excerpt_does_not_modify_the_options_hash
diff --git a/actionview/test/template/url_helper_test.rb b/actionview/test/template/url_helper_test.rb
index bdedbeba92..a087c5c0cd 100644
--- a/actionview/test/template/url_helper_test.rb
+++ b/actionview/test/template/url_helper_test.rb
@@ -539,7 +539,7 @@ class UrlHelperTest < ActiveSupport::TestCase
 
   def test_current_page_with_escaped_params_with_different_encoding
     @request = request_for_url("/")
-    @request.stub(:path, "/category/administra%c3%a7%c3%a3o".force_encoding(Encoding::ASCII_8BIT)) do
+    @request.stub(:path, "/category/administra%c3%a7%c3%a3o".dup.force_encoding(Encoding::ASCII_8BIT)) do
       assert current_page?(controller: "foo", action: "category", category: "administração")
       assert current_page?("http://www.example.com/category/administra%c3%a7%c3%a3o")
     end
diff --git a/activemodel/test/cases/dirty_test.rb b/activemodel/test/cases/dirty_test.rb
index fdd18d7601..0242b96083 100644
--- a/activemodel/test/cases/dirty_test.rb
+++ b/activemodel/test/cases/dirty_test.rb
@@ -96,7 +96,7 @@ class DirtyTest < ActiveModel::TestCase
   end
 
   test "attribute mutation" do
-    @model.instance_variable_set("@name", "Yam")
+    @model.instance_variable_set("@name", "Yam".dup)
     assert !@model.name_changed?
     @model.name.replace("Hadad")
     assert !@model.name_changed?
diff --git a/activemodel/test/cases/type/string_test.rb b/activemodel/test/cases/type/string_test.rb
index 47d412e27e..5bf9fc3527 100644
--- a/activemodel/test/cases/type/string_test.rb
+++ b/activemodel/test/cases/type/string_test.rb
@@ -14,7 +14,7 @@ module ActiveModel
       test "cast strings are mutable" do
         type = Type::String.new
 
-        s = "foo"
+        s = "foo".dup
         assert_equal false, type.cast(s).frozen?
         assert_equal false, s.frozen?
 
diff --git a/activerecord/lib/active_record/associations/join_dependency.rb b/activerecord/lib/active_record/associations/join_dependency.rb
index bc66194aef..04cdcb6a7f 100644
--- a/activerecord/lib/active_record/associations/join_dependency.rb
+++ b/activerecord/lib/active_record/associations/join_dependency.rb
@@ -198,8 +198,7 @@ module ActiveRecord
 
         def table_alias_for(reflection, parent, join)
           name = "#{reflection.plural_name}_#{parent.table_name}"
-          name << "_join" if join
-          name
+          join ? "#{name}_join" : name
         end
 
         def walk(left, right)
diff --git a/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb b/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb
index 61bf5477aa..627b753f01 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb
@@ -679,7 +679,7 @@ module ActiveRecord
           # this block can't be easily moved into attempt_to_checkout_all_existing_connections's
           # rescue block, because doing so would put it outside of synchronize section, without
           # being in a critical section thread_report might become inaccurate
-          msg = "could not obtain ownership of all database connections in #{checkout_timeout} seconds"
+          msg = "could not obtain ownership of all database connections in #{checkout_timeout} seconds".dup
 
           thread_report = []
           @connections.each do |conn|
diff --git a/activerecord/lib/active_record/connection_adapters/abstract/schema_creation.rb b/activerecord/lib/active_record/connection_adapters/abstract/schema_creation.rb
index 93f4529202..8865e7c703 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/schema_creation.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/schema_creation.rb
@@ -22,7 +22,7 @@ module ActiveRecord
         private
 
           def visit_AlterTable(o)
-            sql = "ALTER TABLE #{quote_table_name(o.name)} "
+            sql = "ALTER TABLE #{quote_table_name(o.name)} ".dup
             sql << o.adds.map { |col| accept col }.join(" ")
             sql << o.foreign_key_adds.map { |fk| visit_AddForeignKey fk }.join(" ")
             sql << o.foreign_key_drops.map { |fk| visit_DropForeignKey fk }.join(" ")
@@ -30,17 +30,17 @@ module ActiveRecord
 
           def visit_ColumnDefinition(o)
             o.sql_type = type_to_sql(o.type, o.options)
-            column_sql = "#{quote_column_name(o.name)} #{o.sql_type}"
+            column_sql = "#{quote_column_name(o.name)} #{o.sql_type}".dup
             add_column_options!(column_sql, column_options(o)) unless o.type == :primary_key
             column_sql
           end
 
           def visit_AddColumnDefinition(o)
-            "ADD #{accept(o.column)}"
+            "ADD #{accept(o.column)}".dup
           end
 
           def visit_TableDefinition(o)
-            create_sql = "CREATE#{' TEMPORARY' if o.temporary} TABLE #{quote_table_name(o.name)} "
+            create_sql = "CREATE#{' TEMPORARY' if o.temporary} TABLE #{quote_table_name(o.name)} ".dup
 
             statements = o.columns.map { |c| accept c }
             statements << accept(o.primary_keys) if o.primary_keys
diff --git a/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb b/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb
index 41d900733a..6aed00584a 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb
@@ -1348,7 +1348,7 @@ module ActiveRecord
           sm_table = quote_table_name(ActiveRecord::SchemaMigration.table_name)
 
           if versions.is_a?(Array)
-            sql = "INSERT INTO #{sm_table} (version) VALUES\n"
+            sql = "INSERT INTO #{sm_table} (version) VALUES\n".dup
             sql << versions.map { |v| "(#{quote(v)})" }.join(",\n")
             sql << ";\n\n"
             sql
diff --git a/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb b/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb
index 85d6fbe8b3..9a085df934 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb
@@ -147,7 +147,7 @@ module ActiveRecord
       # this method must only be called while holding connection pool's mutex
       def lease
         if in_use?
-          msg = "Cannot lease connection, "
+          msg = "Cannot lease connection, ".dup
           if @owner == Thread.current
             msg << "it is already leased by the current thread."
           else
diff --git a/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb b/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
index 6a907699e9..062fede1ce 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
@@ -132,7 +132,7 @@ module ActiveRecord
       end
 
       def index_algorithms
-        { default: "ALGORITHM = DEFAULT", copy: "ALGORITHM = COPY", inplace: "ALGORITHM = INPLACE" }
+        { default: "ALGORITHM = DEFAULT".dup, copy: "ALGORITHM = COPY".dup, inplace: "ALGORITHM = INPLACE".dup }
       end
 
       # HELPER METHODS ===========================================
@@ -379,7 +379,7 @@ module ActiveRecord
 
       def add_index(table_name, column_name, options = {}) #:nodoc:
         index_name, index_type, index_columns, _, index_algorithm, index_using, comment = add_index_options(table_name, column_name, options)
-        sql = "CREATE #{index_type} INDEX #{quote_column_name(index_name)} #{index_using} ON #{quote_table_name(table_name)} (#{index_columns}) #{index_algorithm}"
+        sql = "CREATE #{index_type} INDEX #{quote_column_name(index_name)} #{index_using} ON #{quote_table_name(table_name)} (#{index_columns}) #{index_algorithm}".dup
         execute add_sql_comment!(sql, comment)
       end
 
@@ -464,7 +464,7 @@ module ActiveRecord
             super
           end
 
-        sql << " unsigned" if unsigned && type != :primary_key
+        sql = "#{sql} unsigned" if unsigned && type != :primary_key
         sql
       end
 
@@ -778,7 +778,7 @@ module ActiveRecord
           # http://dev.mysql.com/doc/refman/5.7/en/set-statement.html#id944430
           # (trailing comma because variable_assignments will always have content)
           if @config[:encoding]
-            encoding = "NAMES #{@config[:encoding]}"
+            encoding = "NAMES #{@config[:encoding]}".dup
             encoding << " COLLATE #{@config[:collation]}" if @config[:collation]
             encoding << ", "
           end
diff --git a/activerecord/lib/active_record/connection_adapters/mysql/schema_creation.rb b/activerecord/lib/active_record/connection_adapters/mysql/schema_creation.rb
index 083cd6340f..eea4984680 100644
--- a/activerecord/lib/active_record/connection_adapters/mysql/schema_creation.rb
+++ b/activerecord/lib/active_record/connection_adapters/mysql/schema_creation.rb
@@ -16,7 +16,7 @@ module ActiveRecord
           end
 
           def visit_ChangeColumnDefinition(o)
-            change_column_sql = "CHANGE #{quote_column_name(o.name)} #{accept(o.column)}"
+            change_column_sql = "CHANGE #{quote_column_name(o.name)} #{accept(o.column)}".dup
             add_column_position!(change_column_sql, column_options(o.column))
           end
 
@@ -63,7 +63,7 @@ module ActiveRecord
 
           def index_in_create(table_name, column_name, options)
             index_name, index_type, index_columns, _, _, index_using, comment = @conn.add_index_options(table_name, column_name, options)
-            add_sql_comment!("#{index_type} INDEX #{quote_column_name(index_name)} #{index_using} (#{index_columns})", comment)
+            add_sql_comment!("#{index_type} INDEX #{quote_column_name(index_name)} #{index_using} (#{index_columns})".dup, comment)
           end
       end
     end
diff --git a/activerecord/lib/active_record/connection_adapters/mysql/schema_statements.rb b/activerecord/lib/active_record/connection_adapters/mysql/schema_statements.rb
index fc57e41fc9..a01fbba201 100644
--- a/activerecord/lib/active_record/connection_adapters/mysql/schema_statements.rb
+++ b/activerecord/lib/active_record/connection_adapters/mysql/schema_statements.rb
@@ -102,7 +102,7 @@ module ActiveRecord
           def data_source_sql(name = nil, type: nil)
             scope = quoted_scope(name, type: type)
 
-            sql = "SELECT table_name FROM information_schema.tables"
+            sql = "SELECT table_name FROM information_schema.tables".dup
             sql << " WHERE table_schema = #{scope[:schema]}"
             sql << " AND table_name = #{scope[:name]}" if scope[:name]
             sql << " AND table_type = #{scope[:type]}" if scope[:type]
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb b/activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb
index 8a999a8429..a710ea6cc9 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb
@@ -406,7 +406,7 @@ module ActiveRecord
           quoted_table_name = quote_table_name(table_name)
           quoted_column_name = quote_column_name(column_name)
           sql_type = type_to_sql(type, options)
-          sql = "ALTER TABLE #{quoted_table_name} ALTER COLUMN #{quoted_column_name} TYPE #{sql_type}"
+          sql = "ALTER TABLE #{quoted_table_name} ALTER COLUMN #{quoted_column_name} TYPE #{sql_type}".dup
           if options[:collation]
             sql << " COLLATE \"#{options[:collation]}\""
           end
@@ -566,7 +566,7 @@ module ActiveRecord
               super
             end
 
-          sql << "[]" if array && type != :primary_key
+          sql = "#{sql}[]" if array && type != :primary_key
           sql
         end
 
@@ -635,7 +635,7 @@ module ActiveRecord
             scope = quoted_scope(name, type: type)
             scope[:type] ||= "'r','v','m'" # (r)elation/table, (v)iew, (m)aterialized view
 
-            sql = "SELECT c.relname FROM pg_class c LEFT JOIN pg_namespace n ON n.oid = c.relnamespace"
+            sql = "SELECT c.relname FROM pg_class c LEFT JOIN pg_namespace n ON n.oid = c.relnamespace".dup
             sql << " WHERE n.nspname = #{scope[:schema]}"
             sql << " AND c.relname = #{scope[:name]}" if scope[:name]
             sql << " AND c.relkind IN (#{scope[:type]})"
diff --git a/activerecord/lib/active_record/connection_adapters/sqlite3/schema_statements.rb b/activerecord/lib/active_record/connection_adapters/sqlite3/schema_statements.rb
index 00ff804e80..31e83f9260 100644
--- a/activerecord/lib/active_record/connection_adapters/sqlite3/schema_statements.rb
+++ b/activerecord/lib/active_record/connection_adapters/sqlite3/schema_statements.rb
@@ -67,7 +67,7 @@ module ActiveRecord
             scope = quoted_scope(name, type: type)
             scope[:type] ||= "'table','view'"
 
-            sql = "SELECT name FROM sqlite_master WHERE name <> 'sqlite_sequence'"
+            sql = "SELECT name FROM sqlite_master WHERE name <> 'sqlite_sequence'".dup
             sql << " AND name = #{scope[:name]}" if scope[:name]
             sql << " AND type IN (#{scope[:type]})"
             sql
diff --git a/activerecord/lib/active_record/explain.rb b/activerecord/lib/active_record/explain.rb
index 8f7ae2c33c..5e67d16e9f 100644
--- a/activerecord/lib/active_record/explain.rb
+++ b/activerecord/lib/active_record/explain.rb
@@ -16,7 +16,7 @@ module ActiveRecord
     # Returns a formatted string ready to be logged.
     def exec_explain(queries) # :nodoc:
       str = queries.map do |sql, binds|
-        msg = "EXPLAIN for: #{sql}"
+        msg = "EXPLAIN for: #{sql}".dup
         unless binds.empty?
           msg << " "
           msg << binds.map { |attr| render_bind(attr) }.inspect
diff --git a/activerecord/lib/active_record/migration.rb b/activerecord/lib/active_record/migration.rb
index 51c82f4ced..1ff1dcad43 100644
--- a/activerecord/lib/active_record/migration.rb
+++ b/activerecord/lib/active_record/migration.rb
@@ -157,7 +157,7 @@ module ActiveRecord
 
   class ProtectedEnvironmentError < ActiveRecordError #:nodoc:
     def initialize(env = "production")
-      msg = "You are attempting to run a destructive action against your '#{env}' database.\n"
+      msg = "You are attempting to run a destructive action against your '#{env}' database.\n".dup
       msg << "If you are sure you want to continue, run the same command with the environment variable:\n"
       msg << "DISABLE_DATABASE_ENVIRONMENT_CHECK=1"
       super(msg)
@@ -166,7 +166,7 @@ module ActiveRecord
 
   class EnvironmentMismatchError < ActiveRecordError
     def initialize(current: nil, stored: nil)
-      msg =  "You are attempting to modify a database that was last run in `#{ stored }` environment.\n"
+      msg =  "You are attempting to modify a database that was last run in `#{ stored }` environment.\n".dup
       msg << "You are running in `#{ current }` environment. "
       msg << "If you are sure you want to continue, first set the environment using:\n\n"
       msg << "        bin/rails db:environment:set"
@@ -1239,7 +1239,7 @@ module ActiveRecord
           record_version_state_after_migrating(migration.version)
         end
       rescue => e
-        msg = "An error has occurred, "
+        msg = "An error has occurred, ".dup
         msg << "this and " if use_transaction?(migration)
         msg << "all later migrations canceled:\n\n#{e}"
         raise StandardError, msg, e.backtrace
diff --git a/activerecord/lib/active_record/relation/finder_methods.rb b/activerecord/lib/active_record/relation/finder_methods.rb
index df8909379f..eee0f36f63 100644
--- a/activerecord/lib/active_record/relation/finder_methods.rb
+++ b/activerecord/lib/active_record/relation/finder_methods.rb
@@ -334,14 +334,14 @@ module ActiveRecord
       name = @klass.name
 
       if ids.nil?
-        error = "Couldn't find #{name}"
+        error = "Couldn't find #{name}".dup
         error << " with#{conditions}" if conditions
         raise RecordNotFound.new(error, name)
       elsif Array(ids).size == 1
         error = "Couldn't find #{name} with '#{key}'=#{ids}#{conditions}"
         raise RecordNotFound.new(error, name, key, ids)
       else
-        error = "Couldn't find all #{name.pluralize} with '#{key}': "
+        error = "Couldn't find all #{name.pluralize} with '#{key}': ".dup
         error << "(#{ids.join(", ")})#{conditions} (found #{result_size} results, but was looking for #{expected_size})"
 
         raise RecordNotFound.new(error, name, primary_key, ids)
diff --git a/activerecord/lib/active_record/tasks/mysql_database_tasks.rb b/activerecord/lib/active_record/tasks/mysql_database_tasks.rb
index c25d87dd3e..88cbd6f6f5 100644
--- a/activerecord/lib/active_record/tasks/mysql_database_tasks.rb
+++ b/activerecord/lib/active_record/tasks/mysql_database_tasks.rb
@@ -151,7 +151,7 @@ IDENTIFIED BY '#{configuration['password']}' WITH GRANT OPTION;
         end
 
         def run_cmd_error(cmd, args, action)
-          msg = "failed to execute: `#{cmd}`\n"
+          msg = "failed to execute: `#{cmd}`\n".dup
           msg << "Please check the output above for any errors and make sure that `#{cmd}` is installed in your PATH and has proper permissions.\n\n"
           msg
         end
diff --git a/activerecord/test/cases/adapters/postgresql/bytea_test.rb b/activerecord/test/cases/adapters/postgresql/bytea_test.rb
index 539c90f0bc..65baed34e9 100644
--- a/activerecord/test/cases/adapters/postgresql/bytea_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/bytea_test.rb
@@ -47,7 +47,7 @@ class PostgresqlByteaTest < ActiveRecord::PostgreSQLTestCase
   end
 
   def test_type_cast_binary_value
-    data = "\u001F\x8B".force_encoding("BINARY")
+    data = "\u001F\x8B".dup.force_encoding("BINARY")
     assert_equal(data, @type.deserialize(data))
   end
 
diff --git a/activerecord/test/cases/adapters/postgresql/money_test.rb b/activerecord/test/cases/adapters/postgresql/money_test.rb
index 1b5d8362af..ea060345a7 100644
--- a/activerecord/test/cases/adapters/postgresql/money_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/money_test.rb
@@ -47,10 +47,10 @@ class PostgresqlMoneyTest < ActiveRecord::PostgreSQLTestCase
 
   def test_money_type_cast
     type = PostgresqlMoney.type_for_attribute("wealth")
-    assert_equal(12345678.12, type.cast("$12,345,678.12"))
-    assert_equal(12345678.12, type.cast("$12.345.678,12"))
-    assert_equal(-1.15, type.cast("-$1.15"))
-    assert_equal(-2.25, type.cast("($2.25)"))
+    assert_equal(12345678.12, type.cast("$12,345,678.12".dup))
+    assert_equal(12345678.12, type.cast("$12.345.678,12".dup))
+    assert_equal(-1.15, type.cast("-$1.15".dup))
+    assert_equal(-2.25, type.cast("($2.25)".dup))
   end
 
   def test_schema_dumping
@@ -60,7 +60,7 @@ class PostgresqlMoneyTest < ActiveRecord::PostgreSQLTestCase
   end
 
   def test_create_and_update_money
-    money = PostgresqlMoney.create(wealth: "987.65")
+    money = PostgresqlMoney.create(wealth: "987.65".dup)
     assert_equal 987.65, money.wealth
 
     new_value = BigDecimal.new("123.45")
diff --git a/activerecord/test/cases/adapters/sqlite3/sqlite3_adapter_test.rb b/activerecord/test/cases/adapters/sqlite3/sqlite3_adapter_test.rb
index 9a812e325e..cf0c37f70c 100644
--- a/activerecord/test/cases/adapters/sqlite3/sqlite3_adapter_test.rb
+++ b/activerecord/test/cases/adapters/sqlite3/sqlite3_adapter_test.rb
@@ -165,7 +165,7 @@ module ActiveRecord
             data binary
           )
         eosql
-        str = "\x80".force_encoding("ASCII-8BIT")
+        str = "\x80".dup.force_encoding("ASCII-8BIT")
         binary = DualEncoding.new name: "いただきます！", data: str
         binary.save!
         assert_equal str, binary.data
@@ -174,7 +174,7 @@ module ActiveRecord
       end
 
       def test_type_cast_should_not_mutate_encoding
-        name = "hello".force_encoding(Encoding::ASCII_8BIT)
+        name = "hello".dup.force_encoding(Encoding::ASCII_8BIT)
         Owner.create(name: name)
         assert_equal Encoding::ASCII_8BIT, name.encoding
       ensure
diff --git a/activerecord/test/cases/attribute_test.rb b/activerecord/test/cases/attribute_test.rb
index 7cf6b498c9..e856d551c0 100644
--- a/activerecord/test/cases/attribute_test.rb
+++ b/activerecord/test/cases/attribute_test.rb
@@ -76,7 +76,7 @@ module ActiveRecord
     end
 
     test "duping dups the value" do
-      @type.expect(:deserialize, "type cast", ["a value"])
+      @type.expect(:deserialize, "type cast".dup, ["a value"])
       attribute = Attribute.from_database(nil, "a value", @type)
 
       value_from_orig = attribute.value
@@ -244,7 +244,7 @@ module ActiveRecord
     end
 
     test "with_type preserves mutations" do
-      attribute = Attribute.from_database(:foo, "", Type::Value.new)
+      attribute = Attribute.from_database(:foo, "".dup, Type::Value.new)
       attribute.value << "1"
 
       assert_equal 1, attribute.with_type(Type::Integer.new).value
diff --git a/activerecord/test/cases/batches_test.rb b/activerecord/test/cases/batches_test.rb
index fbc3fbb44f..1a66b82b2e 100644
--- a/activerecord/test/cases/batches_test.rb
+++ b/activerecord/test/cases/batches_test.rb
@@ -152,7 +152,7 @@ class EachTest < ActiveRecord::TestCase
   end
 
   def test_find_in_batches_should_not_use_records_after_yielding_them_in_case_original_array_is_modified
-    not_a_post = "not a post"
+    not_a_post = "not a post".dup
     def not_a_post.id; end
     not_a_post.stub(:id, -> { raise StandardError.new("not_a_post had #id called on it") }) do
       assert_nothing_raised do
@@ -417,7 +417,7 @@ class EachTest < ActiveRecord::TestCase
   end
 
   def test_in_batches_should_not_use_records_after_yielding_them_in_case_original_array_is_modified
-    not_a_post = "not a post"
+    not_a_post = "not a post".dup
     def not_a_post.id
       raise StandardError.new("not_a_post had #id called on it")
     end
diff --git a/activerecord/test/cases/binary_test.rb b/activerecord/test/cases/binary_test.rb
index 1fc30e24d2..f6ac7990d1 100644
--- a/activerecord/test/cases/binary_test.rb
+++ b/activerecord/test/cases/binary_test.rb
@@ -10,7 +10,7 @@ unless current_adapter?(:DB2Adapter)
     FIXTURES = %w(flowers.jpg example.log test.txt)
 
     def test_mixed_encoding
-      str = "\x80"
+      str = "\x80".dup
       str.force_encoding("ASCII-8BIT")
 
       binary = Binary.new name: "いただきます！", data: str
diff --git a/activerecord/test/cases/core_test.rb b/activerecord/test/cases/core_test.rb
index 3735572898..936f26ce04 100644
--- a/activerecord/test/cases/core_test.rb
+++ b/activerecord/test/cases/core_test.rb
@@ -35,7 +35,7 @@ class CoreTest < ActiveRecord::TestCase
 
   def test_pretty_print_new
     topic = Topic.new
-    actual = ""
+    actual = "".dup
     PP.pp(topic, StringIO.new(actual))
     expected = <<-PRETTY.strip_heredoc
     #<Topic:0xXXXXXX
@@ -64,7 +64,7 @@ class CoreTest < ActiveRecord::TestCase
 
   def test_pretty_print_persisted
     topic = topics(:first)
-    actual = ""
+    actual = "".dup
     PP.pp(topic, StringIO.new(actual))
     expected = <<-PRETTY.strip_heredoc
     #<Topic:0x\\w+
@@ -92,7 +92,7 @@ class CoreTest < ActiveRecord::TestCase
 
   def test_pretty_print_uninitialized
     topic = Topic.allocate
-    actual = ""
+    actual = "".dup
     PP.pp(topic, StringIO.new(actual))
     expected = "#<Topic:XXXXXX not initialized>\n"
     assert actual.start_with?(expected.split("XXXXXX").first)
@@ -105,7 +105,7 @@ class CoreTest < ActiveRecord::TestCase
         "inspecting topic"
       end
     end
-    actual = ""
+    actual = "".dup
     PP.pp(subtopic.new, StringIO.new(actual))
     assert_equal "inspecting topic\n", actual
   end
diff --git a/activesupport/lib/active_support/cache.rb b/activesupport/lib/active_support/cache.rb
index 3847d8b7ae..3a95d07087 100644
--- a/activesupport/lib/active_support/cache.rb
+++ b/activesupport/lib/active_support/cache.rb
@@ -75,7 +75,7 @@ module ActiveSupport
       #
       # The +key+ argument can also respond to +cache_key+ or +to_param+.
       def expand_cache_key(key, namespace = nil)
-        expanded_cache_key = namespace ? "#{namespace}/" : ""
+        expanded_cache_key = (namespace ? "#{namespace}/" : "").dup
 
         if prefix = ENV["RAILS_CACHE_ID"] || ENV["RAILS_APP_VERSION"]
           expanded_cache_key << "#{prefix}/"
diff --git a/activesupport/lib/active_support/duration/iso8601_serializer.rb b/activesupport/lib/active_support/duration/iso8601_serializer.rb
index e5d458b3ab..1cc731df2b 100644
--- a/activesupport/lib/active_support/duration/iso8601_serializer.rb
+++ b/activesupport/lib/active_support/duration/iso8601_serializer.rb
@@ -15,12 +15,12 @@ module ActiveSupport
         parts, sign = normalize
         return "PT0S".freeze if parts.empty?
 
-        output = "P"
+        output = "P".dup
         output << "#{parts[:years]}Y"   if parts.key?(:years)
         output << "#{parts[:months]}M"  if parts.key?(:months)
         output << "#{parts[:weeks]}W"   if parts.key?(:weeks)
         output << "#{parts[:days]}D"    if parts.key?(:days)
-        time = ""
+        time = "".dup
         time << "#{parts[:hours]}H"     if parts.key?(:hours)
         time << "#{parts[:minutes]}M"   if parts.key?(:minutes)
         if parts.key?(:seconds)
diff --git a/activesupport/lib/active_support/message_encryptor.rb b/activesupport/lib/active_support/message_encryptor.rb
index e576766c64..9225615576 100644
--- a/activesupport/lib/active_support/message_encryptor.rb
+++ b/activesupport/lib/active_support/message_encryptor.rb
@@ -114,7 +114,7 @@ module ActiveSupport
         encrypted_data << cipher.final
 
         blob = "#{::Base64.strict_encode64 encrypted_data}--#{::Base64.strict_encode64 iv}"
-        blob << "--#{::Base64.strict_encode64 cipher.auth_tag}" if aead_mode?
+        blob = "#{blob}--#{::Base64.strict_encode64 cipher.auth_tag}" if aead_mode?
         blob
       end
 
diff --git a/activesupport/lib/active_support/number_helper/number_to_phone_converter.rb b/activesupport/lib/active_support/number_helper/number_to_phone_converter.rb
index 1de9f50f34..3546ee5c2a 100644
--- a/activesupport/lib/active_support/number_helper/number_to_phone_converter.rb
+++ b/activesupport/lib/active_support/number_helper/number_to_phone_converter.rb
@@ -2,7 +2,7 @@ module ActiveSupport
   module NumberHelper
     class NumberToPhoneConverter < NumberConverter #:nodoc:
       def convert
-        str = country_code(opts[:country_code])
+        str = country_code(opts[:country_code]).dup
         str << convert_to_phone_number(number.to_s.strip)
         str << phone_ext(opts[:extension])
       end
diff --git a/activesupport/lib/active_support/xml_mini/libxml.rb b/activesupport/lib/active_support/xml_mini/libxml.rb
index d849cdfa6b..5187316389 100644
--- a/activesupport/lib/active_support/xml_mini/libxml.rb
+++ b/activesupport/lib/active_support/xml_mini/libxml.rb
@@ -53,7 +53,7 @@ module LibXML #:nodoc:
           if c.element?
             c.to_hash(node_hash)
           elsif c.text? || c.cdata?
-            node_hash[CONTENT_ROOT] ||= ""
+            node_hash[CONTENT_ROOT] ||= "".dup
             node_hash[CONTENT_ROOT] << c.content
           end
         end
diff --git a/activesupport/lib/active_support/xml_mini/libxmlsax.rb b/activesupport/lib/active_support/xml_mini/libxmlsax.rb
index f3d485da2f..b1b5517414 100644
--- a/activesupport/lib/active_support/xml_mini/libxmlsax.rb
+++ b/activesupport/lib/active_support/xml_mini/libxmlsax.rb
@@ -21,7 +21,7 @@ module ActiveSupport
       end
 
       def on_start_document
-        @hash = { CONTENT_KEY => "" }
+        @hash = { CONTENT_KEY => "".dup }
         @hash_stack = [@hash]
       end
 
@@ -31,7 +31,7 @@ module ActiveSupport
       end
 
       def on_start_element(name, attrs = {})
-        new_hash = { CONTENT_KEY => "" }.merge!(attrs)
+        new_hash = { CONTENT_KEY => "".dup }.merge!(attrs)
         new_hash[HASH_SIZE_KEY] = new_hash.size + 1
 
         case current_hash[name]
diff --git a/activesupport/lib/active_support/xml_mini/nokogiri.rb b/activesupport/lib/active_support/xml_mini/nokogiri.rb
index 63466c08b2..14176747f9 100644
--- a/activesupport/lib/active_support/xml_mini/nokogiri.rb
+++ b/activesupport/lib/active_support/xml_mini/nokogiri.rb
@@ -57,7 +57,7 @@ module ActiveSupport
             if c.element?
               c.to_hash(node_hash)
             elsif c.text? || c.cdata?
-              node_hash[CONTENT_ROOT] ||= ""
+              node_hash[CONTENT_ROOT] ||= "".dup
               node_hash[CONTENT_ROOT] << c.content
             end
           end
diff --git a/activesupport/lib/active_support/xml_mini/nokogirisax.rb b/activesupport/lib/active_support/xml_mini/nokogirisax.rb
index 54e15e6a5f..902faac312 100644
--- a/activesupport/lib/active_support/xml_mini/nokogirisax.rb
+++ b/activesupport/lib/active_support/xml_mini/nokogirisax.rb
@@ -37,7 +37,7 @@ module ActiveSupport
       end
 
       def start_element(name, attrs = [])
-        new_hash = { CONTENT_KEY => "" }.merge!(Hash[attrs])
+        new_hash = { CONTENT_KEY => "".dup }.merge!(Hash[attrs])
         new_hash[HASH_SIZE_KEY] = new_hash.size + 1
 
         case current_hash[name]
diff --git a/activesupport/lib/active_support/xml_mini/rexml.rb b/activesupport/lib/active_support/xml_mini/rexml.rb
index 03fa910fa5..30e17965a1 100644
--- a/activesupport/lib/active_support/xml_mini/rexml.rb
+++ b/activesupport/lib/active_support/xml_mini/rexml.rb
@@ -74,7 +74,7 @@ module ActiveSupport
           hash
         else
           # must use value to prevent double-escaping
-          texts = ""
+          texts = "".dup
           element.texts.each { |t| texts << t.value }
           merge!(hash, CONTENT_KEY, texts)
         end
diff --git a/activesupport/test/cache/behaviors/cache_store_behavior.rb b/activesupport/test/cache/behaviors/cache_store_behavior.rb
index 03c366e164..4631e6aee8 100644
--- a/activesupport/test/cache/behaviors/cache_store_behavior.rb
+++ b/activesupport/test/cache/behaviors/cache_store_behavior.rb
@@ -196,7 +196,7 @@ module CacheStoreBehavior
   end
 
   def test_original_store_objects_should_not_be_immutable
-    bar = "bar"
+    bar = "bar".dup
     @cache.write("foo", bar)
     assert_nothing_raised { bar.gsub!(/.*/, "baz") }
   end
@@ -285,7 +285,7 @@ module CacheStoreBehavior
   end
 
   def test_really_long_keys
-    key = ""
+    key = "".dup
     900.times { key << "x" }
     assert @cache.write(key, "bar")
     assert_equal "bar", @cache.read(key)
diff --git a/activesupport/test/cache/behaviors/encoded_key_cache_behavior.rb b/activesupport/test/cache/behaviors/encoded_key_cache_behavior.rb
index 4d8e2946b2..6adef2916d 100644
--- a/activesupport/test/cache/behaviors/encoded_key_cache_behavior.rb
+++ b/activesupport/test/cache/behaviors/encoded_key_cache_behavior.rb
@@ -4,7 +4,7 @@
 module EncodedKeyCacheBehavior
   Encoding.list.each do |encoding|
     define_method "test_#{encoding.name.underscore}_encoded_values" do
-      key = "foo".force_encoding(encoding)
+      key = "foo".dup.force_encoding(encoding)
       assert @cache.write(key, "1", raw: true)
       assert_equal "1", @cache.read(key)
       assert_equal "1", @cache.fetch(key)
@@ -16,7 +16,7 @@ module EncodedKeyCacheBehavior
   end
 
   def test_common_utf8_values
-    key = "\xC3\xBCmlaut".force_encoding(Encoding::UTF_8)
+    key = "\xC3\xBCmlaut".dup.force_encoding(Encoding::UTF_8)
     assert @cache.write(key, "1", raw: true)
     assert_equal "1", @cache.read(key)
     assert_equal "1", @cache.fetch(key)
@@ -27,7 +27,7 @@ module EncodedKeyCacheBehavior
   end
 
   def test_retains_encoding
-    key = "\xC3\xBCmlaut".force_encoding(Encoding::UTF_8)
+    key = "\xC3\xBCmlaut".dup.force_encoding(Encoding::UTF_8)
     assert @cache.write(key, "1", raw: true)
     assert_equal Encoding::UTF_8, key.encoding
   end
diff --git a/activesupport/test/cache/cache_key_test.rb b/activesupport/test/cache/cache_key_test.rb
index 149d0f66ee..ea39d7a299 100644
--- a/activesupport/test/cache/cache_key_test.rb
+++ b/activesupport/test/cache/cache_key_test.rb
@@ -45,7 +45,7 @@ class CacheKeyTest < ActiveSupport::TestCase
   end
 
   def test_expand_cache_key_respond_to_cache_key
-    key = "foo"
+    key = "foo".dup
     def key.cache_key
       :foo_key
     end
@@ -53,7 +53,7 @@ class CacheKeyTest < ActiveSupport::TestCase
   end
 
   def test_expand_cache_key_array_with_something_that_responds_to_cache_key
-    key = "foo"
+    key = "foo".dup
     def key.cache_key
       :foo_key
     end
diff --git a/activesupport/test/core_ext/string_ext_test.rb b/activesupport/test/core_ext/string_ext_test.rb
index a98951e889..daa8c3f2ef 100644
--- a/activesupport/test/core_ext/string_ext_test.rb
+++ b/activesupport/test/core_ext/string_ext_test.rb
@@ -233,7 +233,7 @@ class StringInflectionsTest < ActiveSupport::TestCase
 
   def test_string_squish
     original = %{\u205f\u3000 A string surrounded by various unicode spaces,
-      with tabs(\t\t), newlines(\n\n), unicode nextlines(\u0085\u0085) and many spaces(  ). \u00a0\u2007}
+      with tabs(\t\t), newlines(\n\n), unicode nextlines(\u0085\u0085) and many spaces(  ). \u00a0\u2007}.dup
 
     expected = "A string surrounded by various unicode spaces, " \
       "with tabs( ), newlines( ), unicode nextlines( ) and many spaces( )."
@@ -303,8 +303,8 @@ class StringInflectionsTest < ActiveSupport::TestCase
   end
 
   def test_truncate_multibyte
-    assert_equal "\354\225\204\353\246\254\353\236\221 \354\225\204\353\246\254 ...".force_encoding(Encoding::UTF_8),
-      "\354\225\204\353\246\254\353\236\221 \354\225\204\353\246\254 \354\225\204\353\235\274\353\246\254\354\230\244".force_encoding(Encoding::UTF_8).truncate(10)
+    assert_equal "\354\225\204\353\246\254\353\236\221 \354\225\204\353\246\254 ...".dup.force_encoding(Encoding::UTF_8),
+      "\354\225\204\353\246\254\353\236\221 \354\225\204\353\246\254 \354\225\204\353\235\274\353\246\254\354\230\244".dup.force_encoding(Encoding::UTF_8).truncate(10)
   end
 
   def test_truncate_should_not_be_html_safe
@@ -325,7 +325,7 @@ class StringInflectionsTest < ActiveSupport::TestCase
   end
 
   def test_remove!
-    original = "This is a very good day to die"
+    original = "This is a very good day to die".dup
     assert_equal "This is a good day to die", original.remove!(" very")
     assert_equal "This is a good day to die", original
     assert_equal "This is a good day", original.remove!(" to ", /die/)
@@ -658,7 +658,7 @@ end
 
 class OutputSafetyTest < ActiveSupport::TestCase
   def setup
-    @string = "hello"
+    @string = "hello".dup
     @object = Class.new(Object) do
       def to_s
         "other"
@@ -734,7 +734,7 @@ class OutputSafetyTest < ActiveSupport::TestCase
   end
 
   test "Concatting safe onto unsafe yields unsafe" do
-    @other_string = "other"
+    @other_string = "other".dup
 
     string = @string.html_safe
     @other_string.concat(string)
@@ -757,7 +757,7 @@ class OutputSafetyTest < ActiveSupport::TestCase
   end
 
   test "Concatting safe onto unsafe with << yields unsafe" do
-    @other_string = "other"
+    @other_string = "other".dup
     string = @string.html_safe
 
     @other_string << string
@@ -813,7 +813,7 @@ class OutputSafetyTest < ActiveSupport::TestCase
   test "Concatting an integer to safe always yields safe" do
     string = @string.html_safe
     string = string.concat(13)
-    assert_equal "hello".concat(13), string
+    assert_equal "hello".dup.concat(13), string
     assert string.html_safe?
   end
 
@@ -868,7 +868,8 @@ end
 
 class StringIndentTest < ActiveSupport::TestCase
   test "does not indent strings that only contain newlines (edge cases)" do
-    ["", "\n", "\n" * 7].each do |str|
+    ["", "\n", "\n" * 7].each do |string|
+      str = string.dup
       assert_nil str.indent!(8)
       assert_equal str, str.indent(8)
       assert_equal str, str.indent(1, "\t")
diff --git a/activesupport/test/logger_test.rb b/activesupport/test/logger_test.rb
index 3f04783401..1bc443ae65 100644
--- a/activesupport/test/logger_test.rb
+++ b/activesupport/test/logger_test.rb
@@ -37,7 +37,7 @@ class LoggerTest < ActiveSupport::TestCase
     logger = Logger.new f
     logger.level = Logger::DEBUG
 
-    str = "\x80"
+    str = "\x80".dup
     str.force_encoding("ASCII-8BIT")
 
     logger.add Logger::DEBUG, str
@@ -55,7 +55,7 @@ class LoggerTest < ActiveSupport::TestCase
     logger = Logger.new f
     logger.level = Logger::DEBUG
 
-    str = "\x80"
+    str = "\x80".dup
     str.force_encoding("ASCII-8BIT")
 
     logger.add Logger::DEBUG, str
diff --git a/activesupport/test/multibyte_chars_test.rb b/activesupport/test/multibyte_chars_test.rb
index d80d340986..16a7d488c7 100644
--- a/activesupport/test/multibyte_chars_test.rb
+++ b/activesupport/test/multibyte_chars_test.rb
@@ -51,7 +51,7 @@ class MultibyteCharsTest < ActiveSupport::TestCase
   end
 
   def test_forwarded_method_with_non_string_result_should_be_returned_verbatim
-    str = ""
+    str = "".dup
     str.singleton_class.class_eval { def __method_for_multibyte_testing_with_integer_result; 1; end }
     @chars.wrapped_string.singleton_class.class_eval { def __method_for_multibyte_testing_with_integer_result; 1; end }
 
@@ -59,14 +59,14 @@ class MultibyteCharsTest < ActiveSupport::TestCase
   end
 
   def test_should_concatenate
-    mb_a = "a".mb_chars
-    mb_b = "b".mb_chars
+    mb_a = "a".dup.mb_chars
+    mb_b = "b".dup.mb_chars
     assert_equal "ab", mb_a + "b"
     assert_equal "ab", "a" + mb_b
     assert_equal "ab", mb_a + mb_b
 
     assert_equal "ab", mb_a << "b"
-    assert_equal "ab", "a" << mb_b
+    assert_equal "ab", "a".dup << mb_b
     assert_equal "abb", mb_a << mb_b
   end
 
@@ -78,7 +78,7 @@ class MultibyteCharsTest < ActiveSupport::TestCase
 
   def test_concatenation_should_return_a_proxy_class_instance
     assert_equal ActiveSupport::Multibyte.proxy_class, ("a".mb_chars + "b").class
-    assert_equal ActiveSupport::Multibyte.proxy_class, ("a".mb_chars << "b").class
+    assert_equal ActiveSupport::Multibyte.proxy_class, ("a".dup.mb_chars << "b").class
   end
 
   def test_ascii_strings_are_treated_at_utf8_strings
@@ -88,8 +88,8 @@ class MultibyteCharsTest < ActiveSupport::TestCase
   def test_concatenate_should_return_proxy_instance
     assert(("a".mb_chars + "b").kind_of?(@proxy_class))
     assert(("a".mb_chars + "b".mb_chars).kind_of?(@proxy_class))
-    assert(("a".mb_chars << "b").kind_of?(@proxy_class))
-    assert(("a".mb_chars << "b".mb_chars).kind_of?(@proxy_class))
+    assert(("a".dup.mb_chars << "b").kind_of?(@proxy_class))
+    assert(("a".dup.mb_chars << "b".mb_chars).kind_of?(@proxy_class))
   end
 
   def test_should_return_string_as_json
@@ -115,12 +115,12 @@ class MultibyteCharsUTF8BehaviourTest < ActiveSupport::TestCase
   %w{capitalize downcase lstrip reverse rstrip swapcase upcase}.each do |method|
     class_eval(<<-EOTESTS, __FILE__, __LINE__ + 1)
       def test_#{method}_bang_should_return_self_when_modifying_wrapped_string
-        chars = ' él piDió Un bUen café '
+        chars = ' él piDió Un bUen café '.dup
         assert_equal chars.object_id, chars.send("#{method}!").object_id
       end
 
       def test_#{method}_bang_should_change_wrapped_string
-        original = ' él piDió Un bUen café '
+        original = ' él piDió Un bUen café '.dup
         proxy = chars(original.dup)
         proxy.send("#{method}!")
         assert_not_equal original, proxy.to_s
@@ -133,7 +133,7 @@ class MultibyteCharsUTF8BehaviourTest < ActiveSupport::TestCase
   end
 
   def test_tidy_bytes_bang_should_change_wrapped_string
-    original = " Un bUen café \x92"
+    original = " Un bUen café \x92".dup
     proxy = chars(original.dup)
     proxy.tidy_bytes!
     assert_not_equal original, proxy.to_s
@@ -150,7 +150,7 @@ class MultibyteCharsUTF8BehaviourTest < ActiveSupport::TestCase
   end
 
   def test_string_methods_are_chainable
-    assert chars("").insert(0, "").kind_of?(ActiveSupport::Multibyte.proxy_class)
+    assert chars("".dup).insert(0, "").kind_of?(ActiveSupport::Multibyte.proxy_class)
     assert chars("").rjust(1).kind_of?(ActiveSupport::Multibyte.proxy_class)
     assert chars("").ljust(1).kind_of?(ActiveSupport::Multibyte.proxy_class)
     assert chars("").center(1).kind_of?(ActiveSupport::Multibyte.proxy_class)
@@ -195,7 +195,7 @@ class MultibyteCharsUTF8BehaviourTest < ActiveSupport::TestCase
   end
 
   def test_should_use_character_offsets_for_insert_offsets
-    assert_equal "", "".mb_chars.insert(0, "")
+    assert_equal "", "".dup.mb_chars.insert(0, "")
     assert_equal "こわにちわ", @chars.insert(1, "わ")
     assert_equal "こわわわにちわ", @chars.insert(2, "わわ")
     assert_equal "わこわわわにちわ", @chars.insert(0, "わ")
@@ -418,13 +418,13 @@ class MultibyteCharsUTF8BehaviourTest < ActiveSupport::TestCase
   end
 
   def test_slice_bang_removes_the_slice_from_the_receiver
-    chars = "úüù".mb_chars
+    chars = "úüù".dup.mb_chars
     chars.slice!(0, 2)
     assert_equal "ù", chars
   end
 
   def test_slice_bang_returns_nil_and_does_not_modify_receiver_if_out_of_bounds
-    string = "úüù"
+    string = "úüù".dup
     chars = string.mb_chars
     assert_nil chars.slice!(4, 5)
     assert_equal "úüù", chars
diff --git a/activesupport/test/multibyte_test_helpers.rb b/activesupport/test/multibyte_test_helpers.rb
index a70516bb08..e1e0ae86d9 100644
--- a/activesupport/test/multibyte_test_helpers.rb
+++ b/activesupport/test/multibyte_test_helpers.rb
@@ -23,7 +23,7 @@ module MultibyteTestHelpers
 
   UNICODE_STRING = "こにちわ".freeze
   ASCII_STRING = "ohayo".freeze
-  BYTE_STRING = "\270\236\010\210\245".force_encoding("ASCII-8BIT").freeze
+  BYTE_STRING = "\270\236\010\210\245".dup.force_encoding("ASCII-8BIT").freeze
 
   def chars(str)
     ActiveSupport::Multibyte::Chars.new(str)