public async void GetResultsByUserAsync_GivenInvalidUser_ShouldProduceErrorMessage()
{
// arrange
var mockUnitOfWork = new Mock <IUnitOfWork>();
var mockDTOMapper = new Mock <IDTOMapper>();
var evaluationService = new EvaluationService(mockUnitOfWork.Object, mockDTOMapper.Object);
string expected = "username should be alphanumeric";
// act
var actual = await evaluationService.GetResultsByUserAsync("@");
// assert
Assert.Equal(expected, actual.ErrorMessage);
}