3 files changed, 7 insertions, 7 deletions
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