public async Task IdOfNonexistentSupplier_AddSupplierProduct_ReturnNotFound()
{
const int supplierId = -1;
var productModel = new ProductModel();
var exception = await Assert.ThrowsAsync <ProblemDetailsException>(() =>
_suppliersController.AddSupplierProduct(supplierId, productModel));
Assert.Equal(StatusCodes.Status404NotFound, exception.Details.Status);
Assert.Contains("supplier", exception.Details.Title, StringComparison.OrdinalIgnoreCase);
}