public void ThrowIfErrorFailTest()
        {
            //arrange
            var testError = new Exception();

            _task.Reject(testError);

            //act
            Exception realError = null;

            try
            {
                _task.ThrowIfError();
            }
            catch (Exception e)
            {
                realError = e;
            }

            //assert
            Assert.AreEqual(testError, realError);
        }