public void GetNumberOfDays_Returns30() { var date1 = new DateTime(2013, 2, 1); var date2 = new DateTime(2013, 3, 1); var date3 = new DateTime(2013, 4, 1); var date4 = new DateTime(2013, 5, 1); var policy = new Monthly30DayPeriodPolicy(); Assert.That(policy.GetNumberOfDays(date1), Is.EqualTo(30)); Assert.That(policy.GetNumberOfDays(date2), Is.EqualTo(30)); Assert.That(policy.GetNumberOfDays(date3), Is.EqualTo(30)); Assert.That(policy.GetNumberOfDays(date4), Is.EqualTo(30)); }