/**
  * Verify base image on product page(front-end) is displayed correctly
  *
  * @return string|null
  */
 protected function verifyBaseImage()
 {
     if (!$this->productView->isBaseImageVisible()) {
         return 'Base image for product ' . $this->product->getName() . ' is not visible.';
     }
     if (!$this->isImageLoaded($this->productView->getBaseImageSource())) {
         return 'Base image file is corrupted or does not exist for product ' . $this->product->getName();
     }
     return null;
 }