public async Task Given_CreateGrade_When_ModelIsValid_Then_OkStatusCode()
{
// Arrange
var Guid = new Guid("ef7e98df-26ed-4b21-b874-c3a2815d18ac");
var Id = Task.FromResult(Guid);
mockRepo.Setup(g => g.CreateNew(createGradeModel)).Returns(Id);
// Act
var Result = (OkObjectResult)await controller.CreateGrade(createGradeModel);
// Assert
Assert.IsType <OkObjectResult>(Result);
Assert.Equal(Id.Result, Result.Value);
}