public void LoginWithValidUser() { var mock = new Mock<IUserRepository>(); mock.Setup(x => x.GetAll()).Returns(new User[] { new User{ Login = "******", Password="******"} }); var emailMock = new Mock<IEmailSender>(); var target = new UserService(mock.Object, emailMock.Object); var isLogged = target.Login("abcd", "1234"); isLogged.Should().Be(true); }