Make sure assert_initializer accepts a block

Author: rafaelfranca

railties/lib/rails/generators/testing/assertions.rb

@@ -138,8 +138,8 @@ def assert_field_default_value(attribute_type, value)
         #   assert_initializer "mail_interceptors.rb" do |initializer|
         #     assert_match(/SandboxEmailInterceptor/, initializer)
         #   end
-        def assert_initializer(name, *contents)
-          assert_file("config/initializers/#{name}", *contents)
+        def assert_initializer(name, *contents, &block)
+          assert_file("config/initializers/#{name}", *contents, &block)
         end
       end
     end

railties/test/generators/actions_test.rb

@@ -411,7 +411,9 @@ def test_initializer_should_write_date_to_file_with_block_in_config_initializers
       end
     RUBY
     action(:initializer, "constants.rb") { code }
-    assert_initializer "constants.rb", code.strip_heredoc
+    assert_initializer "constants.rb" do |content|
+      assert_equal(content, code.strip_heredoc)
+    end
   end
 
   test "generate" do