public void login_should_authentificate_user_when_user_is_valid() { //Arrange var user = _fixture.Create <MiamUser>(); var loginViewModel = new LoginViewModel() { Email = user.Email, Password = user.Password }; var valideUser = new MayBe <MiamUser>(user); _userAccountService.ValidateUser(loginViewModel.Email, loginViewModel.Password).Returns(valideUser); //Action _accountController.Login(loginViewModel); //Assert _httpContext.Received().AuthenticationSignIn(Arg.Any <ClaimsIdentity>()); }