public async Task PostSupplier_Should_Return_Bad_Request()
{
var delivery = SampleData.GetDeliveries()[1];
deliveryController.ModelState.AddModelError("", "Invalid Date");
var result = await deliveryController.PostDelivery(delivery);
var statusCodeResult = (IStatusCodeActionResult)result.Result;
Assert.IsNull(result.Value);
Assert.AreEqual(statusCodeResult.StatusCode, StatusCodes.Status400BadRequest);
}