[8.x] Add success and failure command assertions

[roberto-aguilar]

After browsing some of my tests for the console commands, I found that I have been doing either:

$this->artisan(FooCommand::class)->assertExitCode(0);
$this->artisan(FooCommand::class)->assertExitCode(1);

or

$this->artisan(FooCommand::class)->assertExitCode(Command::SUCCESS);
$this->artisan(FooCommand::class)->assertExitCode(Command::FAILURE);

With this new set of assertions, this can be unified and by having the IDE to provide auto-completion, writing tests feels smoother:

$this->artisan(FooCommand::class)->assertSuccessful();
$this->artisan(FooCommand::class)->assertFailed();

[taylorotwell]

What about just assertSuccessful and assertFailed?

[roberto-aguilar]

Sounds great, I just renamed the methods.

Thanks for the feedback, @taylorotwell!

[GrahamCampbell]

Wonder if this should assert exit code not equal to zero. Commands can fail with exit codes other than 1.

[roberto-aguilar]

You're totally right, @GrahamCampbell, I updated the implementation based on this 👍

[roberto-aguilar]

The test failures seem unrelated to this PR, but please let me know if I can do anything for them 😃