Issue #2702661 by alexpott, nevergone, GoZ, jibran, dawehner, xjm, hgoto,...

Issue #2702661 by alexpott, nevergone, GoZ, jibran, dawehner, xjm, hgoto, droplet: Make it simple to take screenshots whilst using JavascriptTestBase

core/modules/simpletest/tests/src/FunctionalJavascript/BrowserWithJavascriptTest.php

@@ -53,4 +53,13 @@ public function testAssertJsCondition() {
     $this->assertJsCondition($javascript, 100);
   }
 
+  /**
+   * Tests creating screenshots.
+   */
+  public function testCreateScreenshot() {
+    $this->drupalGet('<front>');
+    $this->createScreenshot('public://screenshot.jpg');
+    $this->assertFileExists('public://screenshot.jpg');
+  }
+
 }

core/tests/Drupal/FunctionalJavascriptTests/JavascriptTestBase.php

@@ -102,6 +102,30 @@ protected function assertJsCondition($condition, $timeout = 1000, $message = '')
     $this->assertTrue($result, $message);
   }
 
+  /**
+   * Creates a screenshot.
+   *
+   * @param string $filename
+   *   The file name of the resulting screenshot. If using the default phantomjs
+   *   driver then this should be a JPG filename.
+   * @param bool $set_background_color
+   *   (optional) By default this method will set the background color to white.
+   *   Set to FALSE to override this behaviour.
+   *
+   * @throws \Behat\Mink\Exception\UnsupportedDriverActionException
+   *   When operation not supported by the driver.
+   * @throws \Behat\Mink\Exception\DriverException
+   *   When the operation cannot be done.
+   */
+  protected function createScreenshot($filename, $set_background_color = TRUE) {
+    $session = $this->getSession();
+    if ($set_background_color) {
+      $session->executeScript("document.body.style.backgroundColor = 'white';");
+    }
+    $image = $session->getScreenshot();
+    file_put_contents($filename, $image);
+  }
+
   /**
    * {@inheritdoc}
    */