public void DeleteEmployeeTest()
        {
            AddEmployeeTest();
            Assert.AreEqual(1, _dataLayer.GetAllEmployees().Count());
            Employee employee = _dataLayer.GetAllEmployees().First();

            _dataLayer.DeleteEmployee(employee);
            Assert.AreEqual(0, _dataLayer.GetAllEmployees().Count());
            Assert.IsNull(_dataLayer.GetEmployee(employee.Id));
        }