Robert Basic's blog

Complex argument matching in Mockery

by Robert Basic on May 08, 2017.

This past weekend I did some issue maintenance and bug triage on Mockery. One thing I noticed going through all these issues, is that people were surprised when learning about the \Mockery::on() argument matcher. I know Mockery’s documentation isn’t the best documentation out there, but this still is a documented feature.

First of all, Mockery supports validating arguments we pass when calling methods on a mock object. This helps us expect a method call with one (set of) argument, but not with an other. For example:

<?php
$mock = \Mockery::mock('AClass');

$mock->shouldReceive('doSomething')
    ->with('A string')
    ->once();

$mock->shouldReceive('doSomething')
    ->with(42)
    ->never();

This will tell Mockery that the doSomething method should receive a call with A string as an argument, once, but never with the number 42 as an argument.

Nice and simple.

But things are not always so simple. Sometimes they are more complicated and complex.

When we need to do a more complex argument matching for an expected method call, the \Mockery::on() matcher comes in really handy. It accepts a closure as an argument and that closure in turn receives the argument passed in to the method, when called. If the closure returns true, Mockery will consider that the argument has passed the expectation. If the closure returns false, or a “falsey” value, the expectation will not pass.

I have used the \Mockery::on() matcher in various scenarios — validating an array argument based on multiple keys and values, complex string matching… and every time it was invaluable. Though, now that I think back, the older the codebase, the higher the usage frequency was. Oh, well.

Say, for example, we have the following code. It doesn’t do much; publishes a post by setting the published flag in the database to 1 and sets the published_at to the current date and time:

<?php
namespace Service;
class Post
{
    public function __construct($model)
    {
        $this->model = $model;
    }

    public function publishPost($id)
    {
        $saveData = [
            'post_id' => $id,
            'published' => 1,
            'published_at' => gmdate('Y-m-d H:i:s'),
        ];
        $this->model->save($saveData);
    }
}

In a test we would mock the model and set some expectations on the call of the save() method:

<?php
$postId = 42;

$modelMock = \Mockery::mock('Model');
$modelMock->shouldReceive('save')
    ->once()
    ->with(\Mockery::on(function ($argument) use ($postId) {
        $postIdIsSet = isset($argument['post_id']) && $argument['post_id'] === $postId;
        $publishedFlagIsSet = isset($argument['published']) && $argument['published'] === 1;
        $publishedAtIsSet = isset($argument['published_at']);

        return $postIdIsSet && $publishedFlagIsSet && $publishedAtIsSet;
    }));

$service = new \Service\Post($modelMock);
$service->publishPost($postId);

\Mockery::close();

The important part of the example is inside the closure we pass to the \Mockery::on() matcher. The $argument is actually the $saveData argument the save() method gets when it is called. We check for a couple of things in this argument:

  • the post ID is set, and is same as the post ID we passed in to the publishPost() method,
  • the published flag is set, and is 1, and
  • the published_at key is present.

If any of these requirements is not satisfied, the closure will return false, the method call expectation will not be met, and Mockery will throw a NoMatchingExpectationException.

Happy hackin’!

Tags: arguments, matching, mockery, mocking, php, testing.
Categories: Development, Programming, Software.

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

To get notified when I write a new blog post or make a new screencast, subscribe:

Recent posts