public void get_monthly_report()
        {
            var aPowerPlant         = new PowerPlant();
            var aBuildingReport     = new BuildingConsumptionReport(Guid.NewGuid(), Power.CreateKilowatts(5));
            var someBuildingsReport = new List <BuildingConsumptionReport> {
                aBuildingReport, aBuildingReport
            };
            var someCitiesReport = new List <CityConsumptionReport> {
                new CityConsumptionReport(Guid.NewGuid(), someBuildingsReport),
                new CityConsumptionReport(Guid.NewGuid(), someBuildingsReport)
            };

            aPowerPlant.GetNotifiedOfElectricConsumeOff(new AreaConsumptionReport(Guid.NewGuid(), someCitiesReport));
            aPowerPlant.GetNotifiedOfElectricConsumeOff(new AreaConsumptionReport(Guid.NewGuid(), someCitiesReport));

            var monthlyReport = aPowerPlant.GetMonthlyReport();

            monthlyReport.TotalGeneratedPower.Should().BeEquivalentTo(OneGigawatt);
            monthlyReport.TotalConsumedPower().Should().BeEquivalentTo(Power.CreateKilowatts(40));
        }