Extend HashWithIndifferentAccess#update to take an optional block

When a block is passed into the method, it will be invoked for each
duplicated key, with the key in question and the two values as
arguments. The value for the duplicated key in the receiver will
be set to the return value of the block.

This behaviour matches Ruby's long-standing implementation of
Hash#update and is intended to provide a more consistent interface.

HashWithIndifferentAccess#merge is also affected by the change, as it
uses #update internally.

1 files changed, 23 insertions, 0 deletions

diff --git a/activesupport/test/core_ext/hash_ext_test.rb b/activesupport/test/core_ext/hash_ext_test.rb
index 4dc9f57038..37fdf1c0af 100644
--- a/activesupport/test/core_ext/hash_ext_test.rb
+++ b/activesupport/test/core_ext/hash_ext_test.rb
@@ -428,6 +428,29 @@ class HashExtTest < ActiveSupport::TestCase
     assert_equal 2, hash['b']
   end
 
+  def test_indifferent_merging_with_block
+    hash = HashWithIndifferentAccess.new
+    hash[:a] = 1
+    hash['b'] = 3
+
+    other = { 'a' => 4, :b => 2, 'c' => 10 }
+
+    merged = hash.merge(other) { |key, old, new| old > new ? old : new }
+
+    assert_equal HashWithIndifferentAccess, merged.class
+    assert_equal 4, merged[:a]
+    assert_equal 3, merged['b']
+    assert_equal 10, merged[:c]
+
+    other_indifferent = HashWithIndifferentAccess.new('a' => 9, :b => 2)
+
+    merged = hash.merge(other_indifferent) { |key, old, new| old + new }
+
+    assert_equal HashWithIndifferentAccess, merged.class
+    assert_equal 10, merged[:a]
+    assert_equal 5, merged[:b]
+  end
+
   def test_indifferent_reverse_merging
     hash = HashWithIndifferentAccess.new('some' => 'value', 'other' => 'value')
     hash.reverse_merge!(:some => 'noclobber', :another => 'clobber')