public void ConvertBackToString()
        {
            //arrange
            string    s    = "Mplus(appdate, 6)-14";
            DiaryDate date = new DiaryDate(s);

            //act
            string result = date.ToFileString();

            //assert
            Assert.AreEqual("MPLUS(appdate,6)-14", result);
        }
        public void ConvertBackToStringwithBonding()
        {
            //arrange
            string    s    = "Str2Date('14/'+copy(mplusstr((appdate),1),4,7))";
            DiaryDate date = new DiaryDate(s);

            //act
            string result = date.ToFileString();

            //assert
            Assert.AreEqual("Str2Date('14/'+copy(mplusstr((appdate),1),4,7))", result);
        }