Integration tests mocking facades vs injecting mocks

Dependency Injection vs Facades

One of the major benefits of Dependency Injection is that code becomes a lot more testable once you start injecting dependencies into methods instead of instantiating/hardcoding them inside the method. This is because you can pass in the dependencies from inside unit tests and they will propagate through the code.

See: http://slashnode.com/dependency-injection/

Dependency Injection stands in stark contrast to Facades. Facades are static global classes, the PHP language does not allow one to overwrite or replace static functions on static classes. The Laravel facades use Mockery to provide mock functionality and they are limited by the same facts as above.

The issue for integration testing can come where you are hoping to retrieve data from a non-mocked Cache but once you use Facade::shouldReceive() then Facade::get() will be overridden by the mocked Cache. The reverse is also true. As a result, Facades are inappropriate where you are interleaving calls for mocked and unmocked data.

In order to test your code with the different data sets that you require, the best practice would be to refactor your legacy code to use DI.

Integration Tests

Easier method

An alternative is to call multiple Facade::shouldReceive() with expectations at the beginning of your integration test. Ensuring that you have the right numbers of expectations in the right order for each of the calls you will make in the integration test. This would probably be the faster way to write tests given your existing codebase.

Harder method

Whilst dependency injection is programming best practice. It could very well be that your codebase has so many legacy classes that it would take an unbelievable amount of time to refactor. In this case, it might be worthwhile considering end-to-end integration tests using a test database with fixtures.

Appendix:

• For how mockery is called by Facade see - function createMockByName(): https://github.com/laravel/framework/blob/5.3/src/Illuminate/Support/Facades/Facade.php
• For examples on chaining mockery calls see fhinkel commented on Feb 6, 2015: https://github.com/padraic/mockery/issues/401