public void GetNetSalarySouldCallTaxCalculatorFactory()
{
Salary grossSalary = SalaryProvider.Get();
ITaxCalculator taxCalculator = Mock.Of <ITaxCalculator>();
Mock.Get(_taxCalculatorFactory)
.Setup(tcf => tcf.GetForCurrency(grossSalary.Currency))
.Returns(taxCalculator);
_service.GetNetSalary(grossSalary);
Mock.Get(_taxCalculatorFactory)
.Verify(tcf => tcf.GetForCurrency(grossSalary.Currency), Times.Once);
}