VerifiedDouble

VerifiedDouble verifies mocks made in the test suite by checking if there are tests against them.

For example, let's say I mocked the created_at method of a model like this:

item = VerifiedDouble.of_instance(Item)
item.should_receive(:created_at).and_return(Time.now)

The item double records its :created_at call. When running the tests, the gem looks for a test that confirms if you can indeed call #created_at on Item. The test should also ensure that the method returns a Time object. Since this is hard to automate, the gem just looks for a test with a tag saying it verifies that contract:

it "tests something", verifies_contract: 'Item#created_at()=>Time' do
  #...
end

If this test does not exist, the gem will complain that the mock is not verified.

More information at https://www.relishapp.com/gsmendoza/verified-double.

References

1. http://www.confreaks.com/videos/2452-railsconf2013-the-magic-tricks-of-testing
2. https://www.relishapp.com/bogus/bogus/v/0-0-3/docs/contract-tests
3. http://www.infoq.com/presentations/integration-tests-scam

Special thanks

To Thomas Sinclair and Inner Core Designs for sponsoring this gem :)