public void ComputeNpvCommand_ShouldComputeNpv()
{
var oneRateLevelOnly = new List <double> {
0.12
};
discountRateLimiter.GetRateLevels(Arg.Any <double>(), Arg.Any <double>(), Arg.Any <double>())
.Returns(oneRateLevelOnly);
var npvParameter = new NpvParameter {
InitialInvestment = -35000
};
var sut = new NpvCalculatorViewModel(discountRateLimiter)
{
NpvParameter = npvParameter,
};
sut.CashFlows.Clear();
sut.CashFlows.Add(new CashFlow {
Cash = 10000, Index = 1
});
sut.CashFlows.Add(new CashFlow {
Cash = 27000, Index = 2
});
sut.CashFlows.Add(new CashFlow {
Cash = 19000, Index = 3
});
sut.ComputeNpvCommand.Execute(null);
sut.NetPresentValues.Count.ShouldBe(1);
Math.Round(sut.NetPresentValues.First().Value, 2).ShouldBe(8976.63);
//ref: https://www.investopedia.com/ask/answers/032615/what-formula-calculating-net-present-value-npv.asp
}
private void ComputeNpvExecute(object param)
{
NetPresentValues.Clear();
var rateLevels = npvCalculator.GetRateLevels(NpvParameter.LowerBoundDiscountRate,
NpvParameter.UpperBoundDiscountRate,
NpvParameter.DiscountRateIncrement);
for (var i = 0; i < rateLevels.Count; i++)
{
NetPresentValues.Add(new NetPresentValue {
Index = i + 1, DiscountRateLevel = rateLevels[i]
});
}
for (var i = 0; i < NetPresentValues.Count; i++)
{
var discountRateLevel = NetPresentValues[i].DiscountRateLevel;
var j = 0;
var totalPresentValue = CashFlows.ToList().Sum(c =>
{
j++;
var presentValue = CalculatePresentValue(c.Cash, discountRateLevel, j);
return(presentValue);
});
NetPresentValues[i].Value = totalPresentValue + NpvParameter.InitialInvestment;
}
HasItems = true;
}