[5.8] Replace only last occurrence to find class name from path on event discovery

[paul-thebaud]

This PR fix the event discovery. When having a Laravel project within /app path (it is the case with Heroku PHP apps), Laravel will replace /app twice because the str_replace is used.

My fix is to use Str::replaceLast as it will only replace the last occurrence.

[antonkomarev]

It will be good to have tests for this case.

[paul-thebaud]

It will be good to have tests for this case.

Since the DiscoverEvents has only static methods, and the Finder is not created using dependency injection, it is hard to test this case without Reflection for protected method.

But I don't know if it is a good idea. Any other thought?

[paul-thebaud]

As @antonkomarev suggested, I added a test for the case mentioned in this PR.

This test use Reflection to only call DiscoverEvents::classFromFile method because the Finder instance cannot be mocked because there is no dependency injection.