toBeAlpha(); expect('123')->not->toBeAlpha(); }); test('failures', function () { expect('123')->toBeAlpha(); })->throws(ExpectationFailedException::class); test('failures with custom message', function () { expect('123')->toBeAlpha('oh no!'); })->throws(ExpectationFailedException::class, 'oh no!'); test('not failures', function () { expect('abc')->not->toBeAlpha(); })->throws(ExpectationFailedException::class);