Sylius\Behat\Page\Admin\ProductVariant\GeneratePageInterface::getValidationMessage PHP Method

    public function getValidationMessage($element, $position);

 /**
  * @Then /^I should be notified that variant code must be unique within this product for the (\d)(?:st|nd|rd|th) variant$/
  */
 public function iShouldBeNotifiedThatVariantCodeMustBeUniqueWithinThisProductForYheVariant($position)
 {
     Assert::same($this->generatePage->getValidationMessage('code', $position - 1), 'This code must be unique within this product.');
 }