public async Task GetAllUsers_Valid() { // Arrange IEnumerable <UserListItemModel> expected = GetSampleData_UserListItems(); _mockAppUsersService.RetrieveAllAsync().Returns(expected); // Act ActionResult <IEnumerable <UserListItemModel> > response = await _sut.GetAllUsers(); // Assert await _mockAppUsersService.Received(1).RetrieveAllAsync(); var createdAtActionResult = Assert.IsType <OkObjectResult>(response.Result); IEnumerable <UserListItemModel> actual = (IEnumerable <UserListItemModel>)createdAtActionResult.Value; Assert.True(actual is not null); for (int i = 0; i < expected.Count(); i++) { Assert.Equal(expected.ElementAt(i).UserId, actual.ElementAt(i).UserId); Assert.Equal(expected.ElementAt(i).UserNameAndEmail, actual.ElementAt(i).UserNameAndEmail); } }