public void AddSupplierRate_ShouldThrowsExceptionWhenStartDateIsGreaterThanEndDate(int endDay)
{
var ex = Assert.Throws <ValidationException>(() =>
_supplierService.AddSupplierRate(1, 10, new DateTime(2015, 8, 2), new DateTime(2015, 8, endDay)));
Assert.AreEqual("The end date must be greater than start date", ex.Message);
}