Скачать или смотреть Resolving Dependency Injection Issues in Laravel Dusk Tests

Discover why dependency injection fails in Laravel Dusk tests and learn how to resolve it using the correct approach in this detailed guide.
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This video is based on the question https://stackoverflow.com/q/69772272/ asked by the user 'Dom' ( https://stackoverflow.com/u/2672338/ ) and on the answer https://stackoverflow.com/a/69772434/ provided by the user 'mrhn' ( https://stackoverflow.com/u/2760986/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Why Can't I Inject a Class in a Test Case with Dusk?

When working with Laravel Dusk for browser testing, you might encounter an issue where you attempt to inject a dependency into your test class, only to be met with a fatal error. This situation can lead to confusion and frustration, as you may expect your Laravel application’s service container to handle this for you.

In this guide, we'll dive into the specifics of why this happens and provide you with a structured solution to overcome this hurdle effectively.

The Problem Scenario

In a recent attempt to test your Laravel project with Dusk, you might have coded your test class like so:

[[See Video to Reveal this Text or Code Snippet]]

However, upon running your test using the command:

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you are greeted by the following error:

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What’s Going Wrong?

The issue here stems from the way test cases are instantiated in Laravel Dusk. Unlike regular classes, Dusk test cases are not instantiated by the container. This means that when PHPUnit initializes your test class, it does so without passing in the dependencies you defined in your constructor. Furthermore, the Laravel application is not fully bootstrapped before the constructor is called, making it impossible for the container to resolve dependencies at that moment.

The Solution: Utilizing the setUp Method

To resolve this issue, you need a different approach. Instead of trying to inject your dependencies through the constructor, you can initialize them within the setUp method. This way, the Laravel application is fully bootstrapped, allowing you to resolve your dependencies correctly.

Step-by-Step Implementation

Here’s how you can implement the solution:

Override the setUp Method: You will create your own setUp method within your test case.

Call the Parent setUp Method: Always remember to call the parent setUp method to ensure that everything is set up properly.

Resolve the Dependency: Use resolve() or app()->make() to get an instance of your repository.

Here’s how the modified code should look:

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Explanation of the Code Changes

setUp Method: This method is designed to set up state before each test is run. By using it, you ensure that your repositories are correctly initialized when the test case begins.

parent::setUp(): This line ensures that any underlying setup logic from the Dusk test case is executed. It’s essential for maintaining the integrity of the test framework’s initialization process.

Dependency Resolution: The resolve() function is a convenient way to fetch a service from the container without needing to pass arguments manually.

Conclusion

Dealing with dependency injection in Laravel Dusk tests can initially seem daunting, but with the right approach, you can overcome these challenges. By utilizing the setUp method for resolving dependencies, you not only align with Laravel’s framework but also ensure your tests run smoothly without encountering instantiation errors.

If you follow the steps outlined above, you'll be well on your way to writing effective tests with Laravel Dusk that leverage the power of dependency injection correctly. Happy testing!