Behat create screenshot on test failure

FeatureContext.php

<?php

use Behat\Mink\Driver\Selenium2Driver;
use Behat\Behat\Event\StepEvent;

/**
 * Take screenshot when step fails.
 * Works only with Selenium2Driver.
 *
 * @AfterStep
 */
  public function takeScreenshotAfterFailedStep(StepEvent $event)
  {
    if (StepEvent::FAILED === $event->getResult()) {
      $driver = $this->getSession()->getDriver();
      if (!($driver instanceof Selenium2Driver)) {
        return;
      }
      $stepNode = $event->getStep();
      $scenarioNode = $stepNode->getParent();
      $featureNode = $scenarioNode->getFeature();
      $directory = '/var/core/';
      $file = $featureNode->getTitle() . '-' . $scenarioNode->getTitle();

      $screenshot = $driver->getWebDriverSession()->screenshot();
      file_put_contents($directory . date('Y-m-d-g-i-s', time()) . '.png', base64_decode($screenshot));
    }
  }