public void AddQuarters()
 {
     var date = new DateTimeOffset(2013, 7, 26, 0, 0, 0, DateTimeOffset.Now.Offset);
     Assert.AreEqual(new DateTimeOffset(2014, 1, 26, 0, 0, 0, DateTimeOffset.Now.Offset), date.AddQuarters(2));
     Assert.AreEqual(new DateTimeOffset(2013, 1, 26, 0, 0, 0, DateTimeOffset.Now.Offset), date.AddQuarters(-2));
 }