Add tests to ensure default proc is used when `HashWithIndifferentAccess' is...

Add tests to ensure default proc is used when `HashWithIndifferentAccess' is initialized with a block

activesupport/test/core_ext/hash_ext_test.rb

@@ -586,6 +586,8 @@ def test_indifferent_to_hash
     roundtrip = mixed_with_default.with_indifferent_access.to_hash
     assert_equal @strings, roundtrip
     assert_equal '1234', roundtrip.default
+
+    # Ensure nested hashes are not HashWithIndiffereneAccess
     new_to_hash = @nested_mixed.with_indifferent_access.to_hash
     assert_not new_to_hash.instance_of?(HashWithIndifferentAccess)
     assert_not new_to_hash["a"].instance_of?(HashWithIndifferentAccess)
@@ -1516,6 +1518,16 @@ def test_from_trusted_xml_allows_symbol_and_yaml_types
     assert_equal expected, Hash.from_trusted_xml('<product><name type="yaml">:value</name></product>')
   end
 
+  def test_should_use_default_proc_for_unknown_key
+    hash_wia = HashWithIndifferentAccess.new { 1 +  2 }
+    assert_equal 3, hash_wia[:new_key]
+  end
+
+  def test_should_use_default_proc_if_no_key_is_supplied
+    hash_wia = HashWithIndifferentAccess.new { 1 +  2 }
+    assert_equal 3, hash_wia.default
+  end
+
   def test_should_use_default_value_for_unknown_key
     hash_wia = HashWithIndifferentAccess.new(3)
     assert_equal 3, hash_wia[:new_key]