public void HasAHashCodeDifferentFromAnObjectThatDiffersByNewValue()
 {
     var different = new ChangeEventArgs<int>(123, 789);
     Assert.AreNotEqual(different.GetHashCode(),
                        ChangeEventArgs.GetHashCode());
 }
 public void HasTheSameHashCodeAsAnEquivalentObject()
 {
     var equivalent = new ChangeEventArgs<int>(123, 456);
     Assert.AreEqual(equivalent.GetHashCode(),
                     ChangeEventArgs.GetHashCode());
 }