Squashed 'libraries/action-scheduler/' content from commit a95f351

git-subtree-dir: libraries/action-scheduler
git-subtree-split: a95f351058eada5e5281faa22e5a40865542e839

tests/phpunit/helpers/ActionScheduler_Callbacks.php

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+<?php
+
+/**
+ * ActionScheduler_Callbacks class.
+ */
+class ActionScheduler_Callbacks {
+	/**
+	 * Scheduled action hook that can be used when we want to simulate an action
+	 * with a registered callback.
+	 */
+	const HOOK_WITH_CALLBACK = 'hook_with_callback';
+
+	/**
+	 * Setup callbacks for different types of hook.
+	 */
+	public static function add_callbacks() {
+		add_action( self::HOOK_WITH_CALLBACK, array( __CLASS__, 'empty_callback' ) );
+	}
+
+	/**
+	 * Remove callbacks.
+	 */
+	public static function remove_callbacks() {
+		remove_action( self::HOOK_WITH_CALLBACK, array( __CLASS__, 'empty_callback' ) );
+	}
+
+	/**
+	 * This stub is used as the callback function for the ActionScheduler_Callbacks::HOOK_WITH_CALLBACK hook.
+	 *
+	 * Action Scheduler will mark actions as 'failed' if a callback does not exist, this
+	 * simply serves to act as the callback for various test scenarios in child classes.
+	 */
+	public static function empty_callback() {}
+}