public string CreateProduct(Product product)
 {
     if (!repo.AddProduct(product))
     {
         return("Error: Database write failed");
     }
     return(null);
 }
 [InlineData("A1=?")]    // mix
 public void AddProductShouldAddProduct(string productName)
 {
     using (var createCtx = new StoreContext(options))
     {
         StoreRepoDB repo        = new StoreRepoDB(createCtx);
         Product     testProduct = new Product();
         testProduct.ProductName  = productName;
         testProduct.ProductPrice = 1;
         repo.AddProduct(testProduct);
         createCtx.SaveChanges();
     }
     using (var assertCtx = new StoreContext(options))
     {
         var result = assertCtx.Products.FirstOrDefault(user => user.ProductName == productName);
         Assert.NotNull(result);
         Assert.Equal(productName, result.ProductName);
     }
 }