public function testToHtmlPreviewImageNote() { /** @var $objectManager \Magento\TestFramework\ObjectManager */ $objectManager = \Magento\TestFramework\Helper\Bootstrap::getObjectManager(); $objectManager->get('Magento\\Framework\\Registry')->register('current_theme', $this->_theme); $this->_block->setArea('adminhtml'); $this->_block->toHtml(); $noticeText = $this->_block->getForm()->getElement('preview_image')->getNote(); $this->assertNotEmpty($noticeText); }