public void ExpiryEndOfQuarterTests() { var endOfQuarterList = new List <DateTime>(); var current = new DateTime(2019, 1, 1); var end = new DateTime(2020, 1, 1); while (current < end) { var endOfQuarter = Expiry.EndOfQuarter(current); endOfQuarterList.Add(endOfQuarter); Assert.AreEqual(1, endOfQuarter.Day); Assert.AreEqual(1, endOfQuarter.Month % 3); Assert.Greater(endOfQuarter, current); current = current.AddDays(1); } var actual = endOfQuarterList.Distinct().Count(); Assert.AreEqual(4, actual); }