Usage in tests

You can run assertions on the Facade

use App\Actions\BuildAndSendSlackAlertAction;
use Hosttech\SlackBlockKitBuilder\Facades\SlackBlockKitBuilder;
use Hosttech\SlackBlockKitBuilder\Blocks\HeaderBlock;

it('sends correct slack alert', function (): void {
    SlackBlockKitBuilder::shouldReceive('make')
            ->once()
            ->andReturn(SlackBlockKitBuilder::getFacadeRoot())
            ->shouldReceive('blocks')
            ->once()
            ->withArgs(fn (array $blocksArg): bool => expect($blockArg)->{0}->toBeInstanceOf(HeaderBlock::class))
            ->andReturn(SlackBlockKitBuilder::getFacadeRoot())
            ->shouldReceive('toArray')
            ->once()
            ->andReturn(['testing']);

    SlackAlert::shouldReceive('blocks')
        ->withArgs(fn (array $blocksArg) => $blocksArg[0] === 'testing');

    // imaginary action we're testing
    resolve(BuildAndSendSlackAlertAction::class)();
});

In the callback of the highlighted line, you can extend the expectation chain, e.g. asserting HeaderBlock has the correct content.