[9.x] Adds partial queue faking

[yoeriboven]

This PR allows you to only fake certain jobs.

Useful if you want to test if one job dispatches another job.

<?php

namespace App\Jobs;

use ...

class ParentJob
{
    public function handle() 
    {
        ChildJob::dispatch();
    }
}

/** @test */
public function it_dispatches_another_job()
{
    Queue::fake(ChildJob::class);

    ParentJob::dispatch();

    Queue::assertPushed(ChildJob::class);
}

When using Queue::fake() all jobs will be faked. Therefore the ParentJob won't run and will never dispatch the ChildJob.

With this addition you can choose which job to fake. Not passing a parameter will fake all jobs like before.

Example: I run a web scraper which scrapes the homepage of a news site in a job. That job will then dispatch a job for every article it found.

[taylorotwell]

One potential problem I see here is the following situation:

Queue::fake(ChildJob::class);

ParentJob::dispatch()->onConnection('non-default-connection');

The ParentJob would be dispatched, but to the wrong connection. This is because QueueFake::connection just returns $this.

This may be solvable by checking the $job->connection property if the job is an object?

[yoeriboven]

I'm not sure I understand what the problem is.

Don't we want to run ParentJob on the queue driver defined in phpunit.xml during testing? (usually sync) Else you'll have to have a queue worker running as well.

[taylorotwell]

The queue driver in the phpunit.xml is just the default driver. Any queued jobs that are dispatched with a different, explicit connection would dispatch to the connection that is explicitly specified. It is possible applications are actually running a queue driver during some integration tests... just thinking of all the possible issues. 🤷‍♂️

[yoeriboven]

I pushed some changes and I suppose this works now.

I'd recommend you to check it yourself since you know a lot more about the queueing system than I do.

[taylorotwell]

OK - just thinking through this from the very beginning.

I would test your original example like so:

Queue::fake();
(new ParentJob)->handle();
Queue::assertPushed(ChildJob::class);

Is there another example you are trying to test that isn't currently already possible?

[yoeriboven]

In that example you'd lose automatic dependency injection in the handle method. I guess you could do it in the constructor but you'll quickly get a lot of parameters in your constructor that way.

The example that made me attempt this PR is when using batches. When you want to test that a job is added to a batch.

class ParentJob
{
    use Batchable, Dispatchable, InteractsWithQueue, Queueable, SerializesModels;

    public function handle() 
    {
        $this->batch()->add(new ChildJob);
    }
{

Queue::fake();

Bus::batch(new ParentJob)->dispatch();

Queue::assertPushed(ChildJob::class);

You can't do (new ParentJob)->handle() because it is not part of a batch. When only faking ChildJob and executing ParentJob you can assert that it was pushed to the queue.

Thinking of it we could also add this:

Queue::fake(ChildJob::class);

$batch = Bus::batch(new ParentJob)->dispatch();

Queue::assertAddedToBatch($batch, ChildJob::class);

[taylorotwell]

Added here: #41425

Thanks