toBeString(); expect(1.1)->not->toBeString(); }); test('failures', function () { expect(null)->toBeString(); })->throws(ExpectationFailedException::class); test('failures with custom message', function () { expect(null)->toBeString('oh no!'); })->throws(ExpectationFailedException::class, 'oh no!'); test('not failures', function () { expect('42')->not->toBeString(); })->throws(ExpectationFailedException::class);