Fix] forgot to add lowercase conversion on grouped product assignation

Author: hitesh-wagento

app/code/Magento/GroupedImportExport/Test/Unit/Model/Import/Product/Type/GroupedTest.php

@@ -198,7 +198,7 @@ public function saveDataProvider()
                 ],
                 'bunch' => [
                     'associated_skus' => 'sku_assoc1=1, sku_assoc2=2',
-                    'sku' => 'productSku',
+                    'sku' => 'productsku',
                     'product_type' => 'grouped'
                 ]
             ],
@@ -211,29 +211,29 @@ public function saveDataProvider()
                 ],
                 'bunch' => [
                     'associated_skus' => '',
-                    'sku' => 'productSku',
+                    'sku' => 'productsku',
                     'product_type' => 'grouped'
                 ]
             ],
             [
                 'skus' => ['newSku' => [],'oldSku' => []],
                 'bunch' => [
                     'associated_skus' => 'sku_assoc1=1, sku_assoc2=2',
-                    'sku' => 'productSku',
+                    'sku' => 'productsku',
                     'product_type' => 'grouped'
                 ]
             ],
             [
                 'skus' => [
                     'newSku' => [
                         'sku_assoc1' => ['entity_id' => 1],
-                        'productSku' => ['entity_id' => 3, 'attr_set_code' => 'Default', 'type_id' => 'grouped']
+                        'productsku' => ['entity_id' => 3, 'attr_set_code' => 'Default', 'type_id' => 'grouped']
                     ],
                     'oldSku' => []
                 ],
                 'bunch' => [
                     'associated_skus' => 'sku_assoc1=1',
-                    'sku' => 'productSku',
+                    'sku' => 'productsku',
                     'product_type' => 'simple'
                 ]
             ]
@@ -257,7 +257,7 @@ public function testSaveDataScopeStore()
 
         $bunch = [[
             'associated_skus' => 'sku_assoc1=1, sku_assoc2=2',
-            'sku' => 'productSku',
+            'sku' => 'productsku',
             'product_type' => 'grouped'
         ]];
         $this->entityModel->expects($this->at(2))->method('getNextBunch')->will($this->returnValue($bunch));