public void DateCalc09_ValidDates()
 {
     Assert.AreEqual("31 days", Ex2hCalculation.DateCalc09("2/1/2000", "1/1/2000"));
 }
 public void DateCalc09_DateParseExceptB()
 {
     Assert.AreEqual("Invalid input", Ex2hCalculation.DateCalc09("1/1/2000", "aaa"));
 }