MAGETWO-80426: Calling the getCustomAttributes() method on a product instance before it is saved, internal _data property structure is changed and extracted incorrectly before saved

- Update unit tests to set custom attribute by CustomAttributesDataInterface;

Author: adifucan

app/code/Magento/Catalog/Test/Unit/Model/CategoryTest.php

@@ -550,7 +550,7 @@ public function testGetCustomAttributes()
         $this->assertEquals("description", $this->category->getCustomAttribute($descriptionAttributeCode)->getValue());
 
         //Change the attribute value, should reflect in getCustomAttribute
-        $this->category->setData($descriptionAttributeCode, "new description");
+        $this->category->setCustomAttribute($descriptionAttributeCode, "new description");
         $this->assertEquals(1, count($this->category->getCustomAttributes()));
         $this->assertNotNull($this->category->getCustomAttribute($descriptionAttributeCode));
         $this->assertEquals(

app/code/Magento/Catalog/Test/Unit/Model/ProductTest.php

@@ -1247,7 +1247,7 @@ public function testGetCustomAttributes()
         $this->assertEquals("red", $this->model->getCustomAttribute($colorAttributeCode)->getValue());
 
         //Change the attribute value, should reflect in getCustomAttribute
-        $this->model->setData($colorAttributeCode, "blue");
+        $this->model->setCustomAttribute($colorAttributeCode, "blue");
         $this->assertEquals(1, count($this->model->getCustomAttributes()));
         $this->assertNotNull($this->model->getCustomAttribute($colorAttributeCode));
         $this->assertEquals("blue", $this->model->getCustomAttribute($colorAttributeCode)->getValue());