Issue #2888231 by mglaman: Attribute widget should respect if order item has a pre-selected purchased entity

Author: mglaman

modules/cart/tests/src/Functional/AddToCartFormTest.php

@@ -74,7 +74,7 @@ public function testVariationCanonicalLinkAddToCartForm() {
 
     $variation1 = $this->createEntity('commerce_product_variation', [
       'type' => 'default',
-      'sku' => $this->randomMachineName(),
+      'sku' => 'not-canonical',
       'price' => [
         'number' => '5.00',
         'currency_code' => 'USD',

modules/product/src/Plugin/Field/FieldWidget/ProductVariationAttributesWidget.php

@@ -128,10 +128,17 @@ public function formElement(FieldItemListInterface $items, $delta, array $elemen
     }
     // Otherwise load from the current context.
     else {
-      $selected_variation = $this->variationStorage->loadFromContext($product);
-      // The returned variation must also be enabled.
-      if (!in_array($selected_variation, $variations)) {
-        $selected_variation = reset($variations);
+      /** @var \Drupal\commerce_order\Entity\OrderItemInterface $order_item */
+      $order_item = $items->getEntity();
+      if (!$order_item->isNew()) {
+        $selected_variation = $order_item->getPurchasedEntity();
+      }
+      else {
+        $selected_variation = $this->variationStorage->loadFromContext($product);
+        // The returned variation must also be enabled.
+        if (!in_array($selected_variation, $variations)) {
+          $selected_variation = reset($variations);
+        }
       }
     }
     $element['variation'] = [