6 files changed, 6 insertions, 8 deletions
diff --git a/actionpack/lib/action_view/helpers/form_helper.rb b/actionpack/lib/action_view/helpers/form_helper.rb
index 3dae1fc87a..6b6a7edc1d 100644
--- a/actionpack/lib/action_view/helpers/form_helper.rb
+++ b/actionpack/lib/action_view/helpers/form_helper.rb
@@ -433,7 +433,7 @@ module ActionView
 
         builder = instantiate_builder(object_name, object, options)
         output  = capture(builder, &block)
-        html_options[:multipart] = builder.multipart?
+        html_options[:multipart] ||= builder.multipart?
 
         form_tag(options[:url] || {}, html_options) { output }
       end
diff --git a/actionpack/lib/action_view/template.rb b/actionpack/lib/action_view/template.rb
index 720890eeb9..946db1df79 100644
--- a/actionpack/lib/action_view/template.rb
+++ b/actionpack/lib/action_view/template.rb
@@ -324,7 +324,8 @@ module ActionView
       end
 
       def locals_code #:nodoc:
-        @locals.map { |key| "#{key} = local_assigns[:#{key}];" }.join
+        # Double assign to suppress the dreaded 'assigned but unused variable' warning
+        @locals.map { |key| "#{key} = #{key} = local_assigns[:#{key}];" }.join
       end
 
       def method_name #:nodoc:
diff --git a/actionpack/test/controller/output_escaping_test.rb b/actionpack/test/controller/output_escaping_test.rb
index 43a8c05cda..c3c549fbfc 100644
--- a/actionpack/test/controller/output_escaping_test.rb
+++ b/actionpack/test/controller/output_escaping_test.rb
@@ -11,8 +11,6 @@ class OutputEscapingTest < ActiveSupport::TestCase
   end
 
   test "escapeHTML shouldn't touch explicitly safe strings" do
-    # TODO this seems easier to compose and reason about, but
-    # this should be verified
     assert_equal "<", ERB::Util.h("<".html_safe)
   end
 
diff --git a/actionpack/test/controller/test_case_test.rb b/actionpack/test/controller/test_case_test.rb
index 9c6d02a62d..38b9794b4d 100644
--- a/actionpack/test/controller/test_case_test.rb
+++ b/actionpack/test/controller/test_case_test.rb
@@ -58,7 +58,7 @@ class TestCaseTest < ActionController::TestCase
     end
 
     def test_headers
-      render text: JSON.dump(request.headers.env)
+      render text: request.headers.env.to_json
     end
 
     def test_html_output
diff --git a/actionpack/test/template/form_helper_test.rb b/actionpack/test/template/form_helper_test.rb
index 268bab6ad2..dff0b8bdc2 100644
--- a/actionpack/test/template/form_helper_test.rb
+++ b/actionpack/test/template/form_helper_test.rb
@@ -2791,8 +2791,8 @@ class FormHelperTest < ActionView::TestCase
   end
 
   def test_form_for_with_html_options_adds_options_to_form_tag
-    form_for(@post, html: { id: 'some_form', class: 'some_class' }) do |f| end
-    expected = whole_form("/posts/123", "some_form", "some_class", method: "patch")
+    form_for(@post, html: { id: 'some_form', class: 'some_class', multipart: true }) do |f| end
+    expected = whole_form("/posts/123", "some_form", "some_class", method: "patch", multipart: "multipart/form-data")
 
     assert_dom_equal expected, output_buffer
   end
diff --git a/actionpack/test/template/url_helper_test.rb b/actionpack/test/template/url_helper_test.rb
index 5d87c96605..e359f47975 100644
--- a/actionpack/test/template/url_helper_test.rb
+++ b/actionpack/test/template/url_helper_test.rb
@@ -51,7 +51,6 @@ class UrlHelperTest < ActiveSupport::TestCase
     assert_equal 'javascript:history.back()', url_for(:back)
   end
 
-  # TODO: missing test cases
   def test_button_to_with_straight_url
     assert_dom_equal %{<form method="post" action="http://www.example.com" class="button_to"><div><input type="submit" value="Hello" /></div></form>}, button_to("Hello", "http://www.example.com")
   end