Ensure HWIA#reverse_merge! retrurns HWIA [#421 state:resolved]

Signed-off-by: Pratik Naik <pratiknaik@gmail.com>

activesupport/lib/active_support/core_ext/hash/indifferent_access.rb

@@ -91,6 +91,12 @@ class HashWithIndifferentAccess < Hash
     self.dup.update(hash)
   end
 
+  # Performs the opposite of merge, with the keys and values from the first hash taking precedence over the second.
+  # This overloaded definition prevents returning a regular hash, if reverse_merge is called on a HashWithDifferentAccess.
+  def reverse_merge(other_hash)
+    super other_hash.with_indifferent_access
+  end
+
   # Removes a specified key from the hash.
   def delete(key)
     super(convert_key(key))

activesupport/test/core_ext/hash_ext_test.rb

@@ -174,6 +174,13 @@ class HashExtTest < Test::Unit::TestCase
     assert_equal 2, hash['b']
   end
 
+  def test_indifferent_reverse_merging
+    hash = HashWithIndifferentAccess.new('some' => 'value', 'other' => 'value')
+    hash.reverse_merge!(:some => 'noclobber', :another => 'clobber')
+    assert_equal 'value', hash[:some]
+    assert_equal 'clobber', hash[:another]
+  end
+
   def test_indifferent_deleting
     get_hash = proc{ { :a => 'foo' }.with_indifferent_access }
     hash = get_hash.call