public void TestGetBirthDay()
{
var bDay = new BirthDay(1, 7, 1987);
Assert.AreEqual("1987-07-01", bDay.GetBirthDay());
var bDay2 = new BirthDay(10, 10, 1990);
Assert.AreEqual("1990-10-10", bDay2.GetBirthDay());
}
