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); }