public void Can_Not_Add_User_With_No_Email() { // Arrange .. instantiate the component under test Mock<IUserRepository> mockRepo = new Mock<IUserRepository>(); _component = new UserComponent(mockRepo.Object); // Arrange .. user object to be added var user = new User(); user.DisplayName = "galilyou"; user.Url = @"http://galilyou.blogspot.com"; // Act .. _component.Add(user); // Assert .. verify the call to Add never happend mockRepo.Verify(c=> c.Add(user), Times.Never()); }