fix(checkout): don't skip the edit page of a one-plan product in the cart

tests/Feature/CheckoutTest.php

@@ -72,6 +72,28 @@ class CheckoutTest extends TestCase
         ]);
     }
 
+    public function test_checkout_page_does_not_redirect_if_one_plan_when_editing_cart_item(): void
+    {
+        $this->get(route('products.checkout', [
+            $this->product->product->category->slug,
+            $this->product->product->slug,
+        ]))->assertRedirect(route('cart'));
+
+        $cart = Cart::where('currency_code', 'USD')->firstOrFail();
+        $item = $cart->items()->firstOrFail();
+
+        Once::flush();
+
+        $response = $this->withCookie('cart', $cart->ulid)->get(route('products.checkout', [
+            $this->product->product->category->slug,
+            $this->product->product->slug,
+            'edit' => $item->id,
+        ]));
+
+        $response->assertStatus(200);
+        $response->assertSee($this->product->product->name);
+    }
+
     public function test_checkout_page_with_multiple_plans(): void
     {
         // Add plan