Drupal 8.0.0 beta 12. More info: https://www.drupal.org/node/2514176

core/lib/Drupal/Core/CronInterface.php

@@ -0,0 +1,25 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Core\CronInterface.
+ */
+
+namespace Drupal\Core;
+
+/**
+ * An interface for running cron tasks.
+ */
+interface CronInterface {
+
+  /**
+   * Executes a cron run.
+   *
+   * Do not call this function from a test. Use $this->cronRun() instead.
+   *
+   * @return bool
+   *   TRUE upon success, FALSE otherwise.
+   */
+  public function run();
+
+}