public void GetEmployeePayrollHistoryTotalNetpay_Should_GetTotal()
        {
            var service = new PayrollService(empStub, uowStub);
            var list    = new List <PayrollHistory>();

            for (int i = 0; i < 4; i++)
            {
                list.Add(new PayrollHistory()
                {
                    GrossIncome = 25000M,
                    NetIncome   = 15000M
                });
            }

            empStub.FindItem(Arg.Any <int>()).Returns(new Employee()
            {
                PayrollHistories = list
            });

            decimal result = service.GetEmployeePayrollHistoryTotalNetpay(Arg.Any <int>());

            Assert.AreEqual(60000M, result);
        }