Return an Enumerator if no block is given

2 files changed, 44 insertions, 0 deletions

diff --git a/activesupport/test/core_ext/hash/transform_keys_test.rb b/activesupport/test/core_ext/hash/transform_keys_test.rb
new file mode 100644
index 0000000000..956fd7ae97
--- /dev/null
+++ b/activesupport/test/core_ext/hash/transform_keys_test.rb
@@ -0,0 +1,32 @@
+require 'abstract_unit'
+require 'active_support/core_ext/hash/transform_keys'
+
+class TransformKeysTest < ActiveSupport::TestCase
+  test "transform_keys returns a new hash with the keys computed from the block" do
+    original = { a: 'a', b: 'b' }
+    mapped = original.transform_keys { |k| "#{k}!".to_sym }
+
+    assert_equal({ a: 'a', b: 'b' }, original)
+    assert_equal({ a!: 'a', b!: 'b' }, mapped)
+  end
+
+  test "transform_keys! modifies the keys of the original" do
+    original = { a: 'a', b: 'b' }
+    mapped = original.transform_keys! { |k| "#{k}!".to_sym }
+
+    assert_equal({ a!: 'a', b!: 'b' }, original)
+    assert_same original, mapped
+  end
+
+  test "transform_keys returns an Enumerator if no block is given" do
+    original = { a: 'a', b: 'b' }
+    enumerator = original.transform_keys
+    assert_equal Enumerator, enumerator.class
+  end
+
+  test "transform_keys is chainable with Enumerable methods" do
+    original = { a: 'a', b: 'b' }
+    mapped = original.transform_keys.with_index { |k, i| [k, i].join.to_sym }
+    assert_equal({ a0: 'a', b1: 'b' }, mapped)
+  end
+end
diff --git a/activesupport/test/core_ext/hash/transform_values_test.rb b/activesupport/test/core_ext/hash/transform_values_test.rb
index 4449c94701..45ed11fef7 100644
--- a/activesupport/test/core_ext/hash/transform_values_test.rb
+++ b/activesupport/test/core_ext/hash/transform_values_test.rb
@@ -46,4 +46,16 @@ class TransformValuesTest < ActiveSupport::TestCase
     assert_equal 'a!', mapped[:a]
     assert_nil mapped[:b]
   end
+
+  test "transform_values returns an Enumerator if no block is given" do
+    original = { a: 'a', b: 'b' }
+    enumerator = original.transform_values
+    assert_equal Enumerator, enumerator.class
+  end
+
+  test "transform_values is chainable with Enumerable methods" do
+    original = { a: 'a', b: 'b' }
+    mapped = original.transform_values.with_index { |v, i| [v, i].join }
+    assert_equal({ a: 'a0', b: 'b1' }, mapped)
+  end
 end