1 files changed, 15 insertions, 1 deletions
diff --git a/activesupport/test/core_ext/hash/transform_keys_test.rb b/activesupport/test/core_ext/hash/transform_keys_test.rb
index a7e12117f3..99af274614 100644
--- a/activesupport/test/core_ext/hash/transform_keys_test.rb
+++ b/activesupport/test/core_ext/hash/transform_keys_test.rb
@@ -18,9 +18,17 @@ class TransformKeysTest < ActiveSupport::TestCase
     assert_same original, mapped
   end
 
-  test "transform_keys returns an Enumerator if no block is given" do
+  test "transform_keys returns a sized Enumerator if no block is given" do
     original = { a: 'a', b: 'b' }
     enumerator = original.transform_keys
+    assert_equal original.size, enumerator.size
+    assert_equal Enumerator, enumerator.class
+  end
+
+  test "transform_keys! returns a sized Enumerator if no block is given" do
+    original = { a: 'a', b: 'b' }
+    enumerator = original.transform_keys!
+    assert_equal original.size, enumerator.size
     assert_equal Enumerator, enumerator.class
   end
 
@@ -29,4 +37,10 @@ class TransformKeysTest < ActiveSupport::TestCase
     mapped = original.transform_keys.with_index { |k, i| [k, i].join.to_sym }
     assert_equal({ a0: 'a', b1: 'b' }, mapped)
   end
+
+  test "transform_keys! is chainable with Enumerable methods" do
+    original = { a: 'a', b: 'b' }
+    original.transform_keys!.with_index { |k, i| [k, i].join.to_sym }
+    assert_equal({ a0: 'a', b1: 'b' }, original)
+  end
 end