public HttpResponseMessage GetGrade(int id)
        {
            var grade = _gradeService.GetGradeById(id);

            return(Request.CreateResponse(HttpStatusCode.OK, grade));
        }
        public void TestMethod_ShouldRetrunGrade()
        {
            var grade = _gradeService.GetGradeById(2);

            Assert.IsNotNull(grade);
        }