Mockery return values based on arguments

published on December 12, 2017.

Sometimes when working with Mockery mock objects, we want to tell a mocked method to return different values for different arguments. It is a rare occasion when I need this feature, but every time I need it, I’m happy it’s there.

The feature that allows us to return different values based on arguments is the andReturnUsing Mockery method, which takes a closure as an argument:

example.php

$dependencyMock = \Mockery::mock('SomeDependency');
$dependencyMock->shouldReceive('callDependency')
    ->andReturnUsing(function ($argument) {
        if ($argument <= 10) {
            return 'low';
        }

        return 'high';
    });

$dependencyMock->callDependency(10); // 'low'
$dependencyMock->callDependency(11); // 'high'

Any number of times we call our callDependency method on our mock object with a number 10 or less, it will return 'low', otherwise it will return 'high'.

Not much of an example, so let’s take a look at one a bit closer to a real world scenario.

Say we’re using Doctrine’s entity manager to get repositories for our entities in a service class:

src/ArticleService.php

<?php

class ArticleService
{
    public function __construct(EntityManager $em)
    {
        $this->articleRepo = $em->getRepository(Entity\Article::class);
        $this->authorRepo = $em->getRepository(Entity\Author::class);
    }
}

Not the best of the codes, but we’ll manage. The entity manager receives two calls to the getRepository method, once for the Article entity, once for the Author entity.

In a test case we could then set up the mocks like so:

tests/ArticleServiceTest.php

<?php

class ArticleServiceTest extends MockeryTestCase
{
    public function setup()
    {
        $this->authorRepositoryMock = \Mockery::mock(AuthorRepository::class);
        $this->articleRepositoryMock = \Mockery::mock(ArticleRepository::class);
        $this->entityManagerMock = \Mockery::mock(EntityManager::class);
    }

    public function testArticleService()
    {
        $repositoryMap = [
            'Entity\Author' => $this->authorRepositoryMock,
            'Entity\Article' => $this->articleRepositoryMock,
        ];
        $this->entityManagerMock->shouldReceive('getRepository')
            ->andReturnUsing(function($argument) use ($repositoryMap) {
                return $repositoryMap[$argument];
            });

        $articleService = new ArticleService($this->entityManagerMock);
    }
}

In the setup method we create the three mock objects that we need and then in the test method we create a $repositoryMap to help us map entities to repositories. The repository map could have been created in the andReturnUsing closure as well.

Now when we instantiate the ArticleService with the mocked entity manager, that mocked entity manager will receive two calls to the getRepository method in the ArticleServices constructor, and it will use the closure defined in andReturnUsing to return the correct repository mock objects.

More than one way to do it

Of course there is another way to achieve the same thing and that’s by using andReturn for the return value expectations, but it’s a bit more to write:

tests/ArticleServiceTest.php

<?php
    public function testArticleService()
    {
        $this->entityManagerMock->shouldReceive('getRepository')
            ->with('Entity\Author')
            ->andReturn($this->authorRepositoryMock);
        $this->entityManagerMock->shouldReceive('getRepository')
            ->with('Entity\Article')
            ->andReturn($this->articleRepositoryMock);

        $articleService = new ArticleService($this->entityManagerMock);
    }

It does the same thing as the previous thing. We might even argue that this second example is even clearer than the first example, sure, for a relatively small argument “map”. But if we need to handle a case with more than just two possible arguments, andReturnUsing can help us in those cases.

Happy hackin’!

P.S.: The proper way to do this actually would be to refactor that ArticleService to not get the two repositories from the entity manager, but to inject them directly instead.

Thanks for reading! If you require help on a project of any kind, let's talk!

Robert Basic

Robert Basic

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