Tests.DateTime_immutability_tests.AddYears_creates_new_immutable_DateTime C# (CSharp) Method

        public void AddYears_creates_new_immutable_DateTime()
        {
            var jan2014 = new DateTime(2014, 01, 01);
            var jan2015 = jan2014.AddYears(1);
            var jan2016 = jan2015.AddYears(1);

            // first object remains unchanged
            Assert.AreEqual(new DateTime(2014, 01, 01), jan2014);

            // second object remains unchanged
            Assert.AreEqual(new DateTime(2015, 01, 01), jan2015);

            Assert.AreEqual(new DateTime(2016, 01, 01), jan2016);
        }
    }