public void VerifyDatesSince()
{
Assert.AreEqual(38795, DateManager.DaysSince(DateManager.TitanicSank, DateTime.Parse("07/03/2018")));
Assert.AreEqual(88387, DateManager.DaysSince(DateManager.AmericanIndependenceDay, DateTime.Parse("07/03/2018")));
Assert.AreEqual(347608, DateManager.DaysSince(DateManager.BattleOfHastings, DateTime.Parse("07/03/2018")));
}