MDL-56898 behat: Try data reset if it fails because of pending process

lib/behat/lib.php

@@ -134,6 +134,13 @@ function behat_error_handler($errno, $errstr, $errfile, $errline, $errcontext) {
         return true;
     }
 
+    // No need to report the before_scenario warning generated to clear last error.
+    // As error_clear_last is only available in php 7.0+, we trigger E_USER_WARNING
+    // to clear any last error which was generated during reset in before_scenario.
+    if (($errno === E_USER_WARNING) && $errstr == 'before_scenario') {
+        return;
+    }
+
     // This error handler receives E_ALL | E_STRICT, running the behat test site the debug level is
     // set to DEVELOPER and will always include E_NOTICE,E_USER_NOTICE... as part of E_ALL, if the current
     // error_reporting() value does not include one of those levels is because it has been forced through
@@ -175,6 +182,14 @@ function behat_shutdown_function() {
     if ($error = error_get_last()) {
         // Ignore E_WARNING, as they might come via ( @ )suppression and might lead to false failure.
         if (isset($error['type']) && !($error['type'] & E_WARNING)) {
+
+            // No need to report the before_scenario warning generated to clear last error.
+            // As error_clear_last is only available in php 7.0+, we trigger E_USER_WARNING
+            // to clear any last error which was generated during reset in before_scenario.
+            if (($error['type'] & E_USER_WARNING) && $error['message'] == 'before_scenario') {
+                return;
+            }
+
             $errors = behat_get_shutdown_process_errors();
 
             $errors[] = $error;

lib/tests/behat/behat_hooks.php

@@ -96,6 +96,13 @@ class behat_hooks extends behat_base {
      */
     protected static $timings = array();
 
+    /**
+     * Keeps track of php error generated during reset.
+     *
+     * @var int keep track of how many php errors were generated.
+     */
+    public static $phperrorduringresetcounter = 0;
+
     /**
      * Hook to capture BeforeSuite event so as to give access to moodle codebase.
      * This will try and catch any exception and exists if anything fails.
@@ -302,7 +309,30 @@ class behat_hooks extends behat_base {
         // Reset $SESSION.
         \core\session\manager::init_empty_session();
 
+        // Set custom handler to try reset all data, if failed because of previous ajax.
+        set_error_handler(
+            function($errno, $errstr, $errfile, $errline) {
+                behat_hooks::$phperrorduringresetcounter++;
+                if (behat_hooks::$phperrorduringresetcounter < self::TIMEOUT) {
+                    sleep(1);
+                    behat_util::reset_all_data();
+                }
+                return true;
+            }, -1 & ~E_NOTICE & ~E_WARNING);
         behat_util::reset_all_data();
+        restore_error_handler();
+
+        // Trigger an error which will be ignored by behat_shutdown_function, this is hacky way to clear last error in php < 7.0.
+        if (self::$phperrorduringresetcounter > 0) {
+            if (function_exists('error_clear_last')) {
+                error_clear_last();
+            } else {
+                trigger_error('before_scenario', E_USER_WARNING);
+            }
+        }
+
+        // Reset the counter here, as this won't be required.
+        self::$phperrorduringresetcounter = 0;
 
         // Assign valid data to admin user (some generator-related code needs a valid user).
         $user = $DB->get_record('user', array('username' => 'admin'));