public void Handle_SignInFailed_ThrowInvalidCredentialsException() { authService.Setup(a => a.SignIn(It.IsAny <string>(), It.IsAny <string>())) .ReturnsAsync(() => null); Assert.That(() => signInCommand.Handle(new SignInRequest(), It.IsAny <CancellationToken>()), Throws.TypeOf <InvalidCredentialsException>()); }