public void GetNextPeriodDateTimeForFirstCall([Values(1,3,6,12)]int period)
        {
            var entity = new StandingOrderEntityImp
            {
                MonthPeriodStep = period,
                ReferenceDay = 1,
                ReferenceMonth = 4,
                FirstBookDate = new DateTime(2014, 4, 1)
            };

            var expectedDateTime = new DateTime(2014, 4, 1);
            var nextDateTime = entity.GetNextPaymentDateTime();

            Assert.That(nextDateTime, Is.EqualTo(expectedDateTime));
        }
        public void GetNextPeriodForLastBookDateReturnsNull([Values(1, 3, 6, 12)]int period)
        {
            var entity = new StandingOrderEntityImp
            {
                MonthPeriodStep = period,
                ReferenceDay = 1,
                ReferenceMonth = 4,
                FirstBookDate = new DateTime(2014, 2, 1),
                LastBookedDate = new DateTime(2014, 4, 1),
                LastBookDate =  new DateTime(2014, 4, 1)
            };

            Assert.That(entity.GetNextPaymentDateTime(), Is.Null);
        }