Test Controller#use_adapter? deprecation

Author: bf4

test/action_controller/serialization_test.rb

@@ -3,6 +3,7 @@
 module ActionController
   module Serialization
     class ImplicitSerializerTest < ActionController::TestCase
+      include ActiveSupport::Testing::Stream
       class ImplicitSerializationTestController < ActionController::Base
         def render_using_implicit_serializer
           @profile = Profile.new({ name: 'Name 1', description: 'Description 1', comments: 'Comments 1' })
@@ -327,6 +328,28 @@ def test_cache_expiration_on_update
         assert_equal 'application/json', @response.content_type
         assert_equal expected.to_json, @response.body
       end
+
+      def test_warn_overridding_use_adapter_as_falsy_on_controller_instance
+        controller = Class.new(ImplicitSerializationTestController) {
+          def use_adapter?
+            false
+          end
+        }.new
+        assert_match /adapter: false/, (capture(:stderr) {
+          controller.get_serializer(@profile)
+        })
+      end
+
+      def test_dont_warn_overridding_use_adapter_as_truthy_on_controller_instance
+        controller = Class.new(ImplicitSerializationTestController) {
+          def use_adapter?
+            true
+          end
+        }.new
+        assert_equal "", (capture(:stderr) {
+          controller.get_serializer(@profile)
+        })
+      end
     end
   end
 end

test/test_helper.rb

@@ -12,6 +12,55 @@
 
 require 'active_model_serializers'
 
+# Use cleaner stream testing interface from Rails 5 if available
+# see https://github.com/rails/rails/blob/29959eb59d/activesupport/lib/active_support/testing/stream.rb
+begin
+  require "active_support/testing/stream"
+rescue LoadError
+  module ActiveSupport
+    module Testing
+      module Stream #:nodoc:
+        private
+
+        def silence_stream(stream)
+          old_stream = stream.dup
+          stream.reopen(IO::NULL)
+          stream.sync = true
+          yield
+        ensure
+          stream.reopen(old_stream)
+          old_stream.close
+        end
+
+        def quietly
+          silence_stream(STDOUT) do
+            silence_stream(STDERR) do
+              yield
+            end
+          end
+        end
+
+        def capture(stream)
+          stream = stream.to_s
+          captured_stream = Tempfile.new(stream)
+          stream_io = eval("$#{stream}")
+          origin_stream = stream_io.dup
+          stream_io.reopen(captured_stream)
+
+          yield
+
+          stream_io.rewind
+          return captured_stream.read
+        ensure
+          captured_stream.close
+          captured_stream.unlink
+          stream_io.reopen(origin_stream)
+        end
+      end
+    end
+  end
+end
+
 class Foo < Rails::Application
   if Rails::VERSION::MAJOR >= 4
     config.eager_load = false