MTO-134: [Variation] Add Simple Product with required Custom Options to Cart

- Defects fixed

Author: vitalysery

dev/tests/functional/tests/app/Magento/Backend/Test/Block/Messages.php

@@ -22,11 +22,11 @@ class Messages extends Block
     protected $successMessage = '[data-ui-id$=message-success]';
 
     /**
-     * "This is a required field." validation error message.
+     * Selector for "This is a required field." validation error message.
      *
      * @var string
      */
-    protected $validationErrorMessage = '//div[@class="mage-error"][contains(text(), "This is required field")]';
+    private $validationErrorMessage = '//div[@class="mage-error"][contains(text(), "This is required field")]';
 
     /**
      * Last success message selector.

dev/tests/functional/tests/app/Magento/Catalog/Test/Block/Product/View/CustomOptions.php

@@ -195,13 +195,10 @@ protected function getListOptions()
      */
     public function validationErrorMessageIsVisible($customOptionTitle)
     {
-        return $this->_rootElement
-            ->find(
-                sprintf(
-                    $this->customOptionField . $this->requiredOption . $this->validationErrorMessage, $customOptionTitle
-                ),
-                Locator::SELECTOR_XPATH
-            )->isVisible() ? true : false;
+        $optionSelector = $this->customOptionField . $this->requiredOption . $this->validationErrorMessage;
+        $title = sprintf($optionSelector, $customOptionTitle);
+
+        return $this->_rootElement->find($title, Locator::SELECTOR_XPATH)->isVisible();
     }
 
     /**