public void ActualPrice_FirstRangeIsLimitless_PreviousRangeTakeIntoAccount()
        {
            var consumed = 50;

            _tariff.Prices = new[]
            {
                new UtilityPrice(30, null, -0.123m),
                new UtilityPrice(0, 100, 0.91m),
                new UtilityPrice(100, null, 1.68m),
            };

            var totalPrice = _tariff.ActualPrice(consumed);

            var expected = 30 * .91m + 20 * (-.123m);

            totalPrice.Should().Be(expected);
        }
        public void ActualPrice_WithinFirstRange_ConsumedTimesPrice()
        {
            var consumed = 50;

            var totalPrice = _tariff.ActualPrice(consumed);

            var expected = consumed * _tariff.Prices.First().Price;

            totalPrice.Should().Be(expected);
        }