4 files changed, 15 insertions, 7 deletions
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 222083817e..5bf9fc3527 100644
--- a/activemodel/test/cases/type/string_test.rb
+++ b/activemodel/test/cases/type/string_test.rb
@@ -12,16 +12,25 @@ module ActiveModel
       end
 
       test "cast strings are mutable" do
-        s = "foo"
         type = Type::String.new
+
+        s = "foo".dup
         assert_equal false, type.cast(s).frozen?
+        assert_equal false, s.frozen?
+
+        f = "foo".freeze
+        assert_equal false, type.cast(f).frozen?
+        assert_equal true, f.frozen?
       end
 
       test "values are duped coming out" do
-        s = "foo"
         type = Type::String.new
+
+        s = "foo"
         assert_not_same s, type.cast(s)
+        assert_equal s, type.cast(s)
         assert_not_same s, type.deserialize(s)
+        assert_equal s, type.deserialize(s)
       end
     end
   end
diff --git a/activemodel/test/cases/validations/format_validation_test.rb b/activemodel/test/cases/validations/format_validation_test.rb
index d7e6bf3707..f5b1ad721c 100644
--- a/activemodel/test/cases/validations/format_validation_test.rb
+++ b/activemodel/test/cases/validations/format_validation_test.rb
@@ -107,7 +107,7 @@ class PresenceValidationTest < ActiveModel::TestCase
   end
 
   def test_validates_format_of_with_lambda
-    Topic.validates_format_of :content, with: lambda { |topic| topic.title == "digit" ? /\A\d+\Z/ : /\A\S+\Z/ }
+    Topic.validates_format_of :content, with: lambda { |topic| topic.title == "digit" ? /\A\d+\z/ : /\A\S+\z/ }
 
     t = Topic.new
     t.title = "digit"
@@ -119,7 +119,7 @@ class PresenceValidationTest < ActiveModel::TestCase
   end
 
   def test_validates_format_of_without_lambda
-    Topic.validates_format_of :content, without: lambda { |topic| topic.title == "characters" ? /\A\d+\Z/ : /\A\S+\Z/ }
+    Topic.validates_format_of :content, without: lambda { |topic| topic.title == "characters" ? /\A\d+\z/ : /\A\S+\z/ }
 
     t = Topic.new
     t.title = "characters"
@@ -131,7 +131,7 @@ class PresenceValidationTest < ActiveModel::TestCase
   end
 
   def test_validates_format_of_for_ruby_class
-    Person.validates_format_of :karma, with: /\A\d+\Z/
+    Person.validates_format_of :karma, with: /\A\d+\z/
 
     p = Person.new
     p.karma = "Pixies"
diff --git a/activemodel/test/validators/email_validator.rb b/activemodel/test/validators/email_validator.rb
index 9b74d83b37..f733c45cf0 100644
--- a/activemodel/test/validators/email_validator.rb
+++ b/activemodel/test/validators/email_validator.rb
@@ -1,4 +1,3 @@
-
 class EmailValidator < ActiveModel::EachValidator
   def validate_each(record, attribute, value)
     record.errors[attribute] << (options[:message] || "is not an email") unless