public void TestImmutabilityWhenChangingExpirationDate()
 {
     DiscountByDate original = new DiscountByDate(.1m, DateTime.Now);
     DiscountByDate verifier = new DiscountByDate(original);
     DiscountByDate extended = original.ExtendByDays(7);
     Assert.IsFalse(original.Equals(extended));
     Assert.IsTrue(original.Equals(verifier));
 }
 public void TestMatchSameValues()
 {
     DiscountByDate discount = new DiscountByDate(.1m, DateTime.Now);
     DiscountByDate identicalDiscount = new DiscountByDate(discount);
     Assert.IsTrue(discount.Equals(identicalDiscount));
 }
 public void TestMatchSameDateObject()
 {
     DiscountByDate discount = new DiscountByDate(.1m, DateTime.Now);
     Assert.IsTrue(discount.Equals(discount));
 }
 public void TestMatchDifferentValues()
 {
     DiscountByDate discount = new DiscountByDate(.1m, DateTime.Now);
     DiscountByDate differentDiscount = new DiscountByDate(.1m, DateTime.Today);
     Assert.IsFalse(discount.Equals(differentDiscount));
 }