Issue #3211164 by alexpott: Random errors in Javascript Testing

core/tests/Drupal/FunctionalJavascriptTests/WebDriverCurlService.php

@@ -14,6 +14,25 @@ use WebDriver\Exception as WebDriverException;
  */
 class WebDriverCurlService extends CurlService {
 
+  /**
+   * The maximum number of times to try in the event of a stale element
+   * reference error.
+   *
+   * @var int
+   */
+  private static $maxRetries = 10;
+
+  /**
+   * Sets the maximum number of retries.
+   *
+   * @param int $max_retries
+   *   The maximum number of times to try in the event of a stale element
+   *   reference error. This number must be greater than 10.
+   */
+  public static function setMaxRetries(int $max_retries) {
+    static::$maxRetries = max($max_retries, static::$maxRetries);
+  }
+
   /**
    * {@inheritdoc}
    */
@@ -22,7 +41,7 @@ class WebDriverCurlService extends CurlService {
       CURLOPT_FAILONERROR => TRUE,
     ];
     $retries = 0;
-    while ($retries < 10) {
+    while ($retries < static::$maxRetries) {
       try {
         $customHeaders = [
           'Content-Type: application/json;charset=UTF-8',
@@ -104,8 +123,9 @@ class WebDriverCurlService extends CurlService {
 
         $result = json_decode($rawResult, TRUE);
         if (isset($result['status']) && $result['status'] === WebDriverException::STALE_ELEMENT_REFERENCE) {
-          usleep(100000);
           $retries++;
+          // Wait a bit longer each time a stale reference error has occurred.
+          usleep(100000 * $retries);
           continue;
         }
         return [$rawResult, $info];

core/tests/Drupal/FunctionalJavascriptTests/WebDriverTestBase.php

@@ -31,6 +31,15 @@ abstract class WebDriverTestBase extends BrowserTestBase {
    */
   protected $minkDefaultDriverClass = DrupalSelenium2Driver::class;
 
+  /**
+   * The maximum number of times to try a webdriver request.
+   *
+   * @var int
+   *
+   * @see \Drupal\FunctionalJavascriptTests\WebDriverCurlService::$maxRetries
+   */
+  protected const WEBDRIVER_RETRIES = 10;
+
   /**
    * {@inheritdoc}
    */
@@ -39,6 +48,7 @@ abstract class WebDriverTestBase extends BrowserTestBase {
       throw new \UnexpectedValueException(sprintf("%s has to be an instance of %s", $this->minkDefaultDriverClass, DrupalSelenium2Driver::class));
     }
     $this->minkDefaultDriverArgs = ['chrome', NULL, 'http://localhost:4444'];
+    WebDriverCurlService::setMaxRetries(max((int) getenv('WEBDRIVER_RETRIES'), static::WEBDRIVER_RETRIES));
 
     try {
       return parent::initMink();