unit testing Mail::send()

Say I'm sending an email with \Illuminate\Support\Facades\Mail::send(). How would I test this to see if an email had in fact been sent?

https://laravel.com/docs/5.8/mocking#mail-fake mentions Mail::assertSent() but that requires you a pass to it a @param string $mailable variable and idk what that variable would need to be with Mail::send().

Any ideas?

via Chebli Mohamed