Behat context for obtaining screenshots on step failure.

FailureContext.php

<?php

use Behat\Mink\Driver\Selenium2Driver;
use Behat\Behat\Hook\Scope\AfterStepScope;
use Behat\Mink\Mink;
use Behat\MinkExtension\Context\MinkAwareContext;

/**
 * Class FailureContext.
 *
 * Saves markup (and screenshots for JS-enabled browsers) for failed steps. Also
 * provides a step to take a screenshot during a test execution.
 *
 * Add to `behat.yml` with:
 *
 * @code
 * - FailureContext:
 *     failure_path: '../failures'
 * @endcode
 */
class FailureContext implements MinkAwareContext {

  /**
   * Where to write the failures.
   *
   * @var string
   */
  protected $failurePath;

  /**
   * Mink parameters.
   *
   * @var \Behat\Mink\Mink
   */
  protected $mink;

  /**
   * Mink instance.
   *
   * @var array
   */
  protected $minkParameters = [];

  /**
   * FailureContext constructor.
   *
   * @param string $failure_path
   *   Where to write the failures.
   */
  public function __construct($failure_path) {
    $this->failurePath = $failure_path;
    if (!file_exists($failure_path)) {
      @mkdir($failure_path, 0755, TRUE);
    }
  }

  /**
   * Step for capturing a screenshot.
   *
   * @Then I take a screenshot
   */
  public function assertScreenShot() {
    $fileName = $this->failurePath . '/screenshot-' . date('Ymd_His');
    $this->dumpMarkup($fileName);
    $this->screenShot($fileName);
  }

  /**
   * Analyzes the result of a step and performs dump/screenshot if failed.
   *
   * @param \Behat\Behat\Hook\Scope\AfterStepScope $scope
   *   The AfterStepScope for the failed step.
   *
   * @AfterStep
   */
  public function handleFailure(AfterStepScope $scope) {
    if (99 !== $scope->getTestResult()->getResultCode()) {
      return;
    }

    $fileName = $this->fileName($scope);
    $this->dumpMarkup($fileName);
    $this->screenShot($fileName);
  }

  /**
   * Compute a file name for a failed step output.
   *
   * @param \Behat\Behat\Hook\Scope\AfterStepScope $scope
   *   The AfterStepScope for the failed step.
   *
   * @return string
   *   The resulting filename including path.
   */
  protected function fileName(AfterStepScope $scope) {
    $baseName = pathinfo($scope->getFeature()->getFile());
    $baseName = substr($baseName['basename'], 0, strlen($baseName['basename']) - strlen($baseName['extension']) - 1);
    $baseName .= '-' . $scope->getStep()->getLine();
    $baseName .= '-' . date('Ymd_His');
    $baseName = $this->failurePath . '/' . $baseName;
    return $baseName;
  }

  /**
   * Save the markup from the failed step.
   *
   * @param string $fileName
   *   The full path and name of the file to write.
   */
  protected function dumpMarkup($fileName) {
    @mkdir($this->failurePath, 0755, TRUE);
    $fileName .= '.html';
    $html = $this->mink->getSession()->getPage()->getContent();
    file_put_contents($fileName, $html);
    sprintf("HTML available at: %s\n", $fileName);
  }

  /**
   * Save a screen shot from the failed step.
   *
   * @param string $fileName
   *   The full path and name of the file to write.
   */
  protected function screenShot($fileName) {
    $fileName .= '.png';
    $driver = $this->mink->getSession()->getDriver();

    if ($driver instanceof Selenium2Driver) {
      file_put_contents($fileName, $this->mink->getSession()->getDriver()->getScreenshot());
      sprintf("Screen shot available at: %s\n", $fileName);
      return;
    }
  }

  /**
   * {@inheritdoc}
   */
  public function setMink(Mink $mink) {
    $this->mink = $mink;
  }

  /**
   * {@inheritdoc}
   */
  public function setMinkParameters(array $parameters) {
    $this->minkParameters = $parameters;
  }

}