public async Task SlowExercise()
        {
            var exercises = new IExerciseDefinition[]
            {
                new LongCalculationExercise(),
            };

            var errors = await TimeValidation.GetErrors(exercises);

            Assert.AreEqual(1, errors.Count, string.Join(",", errors));
        }
        public async Task ValidExercise()
        {
            var exercises = new IExerciseDefinition[]
            {
                new ValidExercise()
            };

            var errors = await TimeValidation.GetErrors(exercises);

            Assert.AreEqual(0, errors.Count, string.Join(",", errors));
        }