public void Calculate_WithLongStayFromSundayToTuesday_ReturnsCorrectCharge()
        {
            // arrange
            var start = new DateTime(2020, 4, 5);
            var end   = new DateTime(2020, 4, 7);
            var stay  = new LongStay(start, end);

            // act
            var charge = chargeCalculator.Calculate(stay);

            // assert
            // charge should be for 3 full days: £7.5
            Assert.IsTrue(charge == 22.5M);
        }
        public void Calculate_WithLongStayFromMidnightToEndOfCurrentDay_ReturnsCorrectCharge()
        {
            // arrange
            var start = new DateTime(2020, 3, 30);
            var end   = new DateTime(2020, 3, 30, 23, 59, 59);
            var stay  = new LongStay(start, end);

            // act
            var charge = chargeCalculator.Calculate(stay);

            // assert
            // charge should be for one full day: £7.5
            Assert.IsTrue(charge == 7.5M);
        }