feat: process a specific message from the queue

[podoko]

Hello, I needed the same feature as described in #72 so I tried to implement it.

This pr aims at allowing tests to process a specific message present in a queue when many are present but only the behavior of a specific one is being tested

Closes #72

[nikophil]

while I like the idea, I'm not sure about the implementation: we should not store the filter like any other configuration.

I think the right thing to do here is some kind of decorator:

final class TestTransport implements TransportInterface
{
  public function process(int|callable|string $numberOrFilter = -1): self
  {
      // ...

      if (\is_int($numberOrFilter)) {
          $number = $numberOrFilter;
          $receiver = $this;
      } else {
          $number = 1;
          $receiver = new FilteredReceiver($this, EnvelopeFilter::normalize($numberOrFilter));
      }

      $worker = new Worker([$this->name => $receiver], $this->bus, $this->dispatcher);

      // ...
  }

  public function get(): iterable
  {
      return $this->getMatching(null);
  }

   /** @internal */
  public function getMatching(?callable $filter): iterable
  {
     // ... basically everything which is currently in `TestTransport::get()`
  }
}

 /** @internal */
 final class FilteredReceiver implements ReceiverInterface
 {
     /** @param \Closure(Envelope):bool $filter */
     public function __construct(
        private readonly TestTransport $decorated, 
        private readonly \Closure $filter,
    ) {}

     public function get(): iterable
     {
         return $this->decorated->getMatching($this->filter); 
     }

     // ... other method from ReceiverInterface should defer to $decorated
}

[nikophil]

please, don't use a static method, but make this class concrete and invokable.

Then, then method TestTransport::getMatching() I am talking in the other comment will look like this:

 /** @internal */
public function getMatching(?EnvelopeFilter $filter): iterable