public async void UserServiceRegisterUserTest() { // arrange var mockedResult = new MockIdentityResult().MockResultSuccession(true); var testPassword = _fixture.Create <string>(); // create a registration model with same email as the test user var registrationModel = new RegisterResult { Result = mockedResult, User = _testUser }; _mockUserManager .Setup(x => x.CreateAsync(_testUser, testPassword)) .Returns(Task.FromResult((IdentityResult)mockedResult)); var usersList = new List <User> { _testUser }; var mockUsers = usersList.AsQueryable().BuildMock(); _mockUserManager.Setup(x => x.Users).Returns(mockUsers.Object); var userService = MockUserService.GetMockUserService( signInManager: MockSignInManager.GetMockSignInManager(userManager: _mockUserManager.Object).Object, userManager: _mockUserManager.Object, roleManager: _mockRoleManager.Object ).Object; // act var result = await userService.RegisterUser(_testUser, testPassword, _groupListNames); // assert registrationModel.ToExpectedObject().ShouldMatch(result); }