From 05f28947e767d3a5b312ee840e70538f1fadb9be Mon Sep 17 00:00:00 2001
From: Sergey Biryukov <sergeybiryukov@git.wordpress.org>
Date: Thu, 19 Aug 2021 12:43:03 +0000
Subject: [PATCH] Media: Check the return type of `_get_cron_array()` in
 `WP_Media_List_Table::prepare_items()`.
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The following warnings could, in very select circumstances, be shown:
{{{
// PHP 8.0 and higher:
Warning: foreach() argument must be of type array|object, bool given

// PHP 5.6 – 7.4
Warning: Invalid argument supplied for foreach()
}}}

In `WP_Media_List_Table::prepare_items()`, the cron info array is retrieved via a call to `_get_cron_array()`, but as the documentation (correctly) states, the return type of that function is `array|false`, where `false` is returned for a virgin site, with no cron jobs scheduled yet.

However, no type check is done on the return value, and the method just blindly continues by using it in a `foreach`.

Fixed by adding validation for the returned value from `_get_cron_array()` and only running the `foreach` when the returned value is an array.

Reference: [https://developer.wordpress.org/reference/functions/_get_cron_array/ WordPress Developer Resources: _get_cron_array()]

Follow-up to [48417].

Props jrf, hellofromTonya, mukesh27.
Fixes #53949.

git-svn-id: https://develop.svn.wordpress.org/trunk@51638 602fd350-edb4-49c9-b593-d223f7449a82
---
 .../includes/class-wp-media-list-table.php    | 14 ++++--
 .../tests/admin/includesMediaListTable.php    | 50 +++++++++++++++++++
 2 files changed, 59 insertions(+), 5 deletions(-)
 create mode 100644 tests/phpunit/tests/admin/includesMediaListTable.php

diff --git a/src/wp-admin/includes/class-wp-media-list-table.php b/src/wp-admin/includes/class-wp-media-list-table.php
index b3eb0b32cc..275d07caca 100644
--- a/src/wp-admin/includes/class-wp-media-list-table.php
+++ b/src/wp-admin/includes/class-wp-media-list-table.php
@@ -78,12 +78,16 @@ class WP_Media_List_Table extends WP_List_Table {
 		 */
 		$not_in = array();
 
-		foreach ( _get_cron_array() as $cron ) {
-			if ( isset( $cron['upgrader_scheduled_cleanup'] ) ) {
-				$details = reset( $cron['upgrader_scheduled_cleanup'] );
+		$crons = _get_cron_array();
 
-				if ( ! empty( $details['args'][0] ) ) {
-					$not_in[] = (int) $details['args'][0];
+		if ( is_array( $crons ) ) {
+			foreach ( $crons as $cron ) {
+				if ( isset( $cron['upgrader_scheduled_cleanup'] ) ) {
+					$details = reset( $cron['upgrader_scheduled_cleanup'] );
+
+					if ( ! empty( $details['args'][0] ) ) {
+						$not_in[] = (int) $details['args'][0];
+					}
 				}
 			}
 		}
diff --git a/tests/phpunit/tests/admin/includesMediaListTable.php b/tests/phpunit/tests/admin/includesMediaListTable.php
new file mode 100644
index 0000000000..da0aef19f2
--- /dev/null
+++ b/tests/phpunit/tests/admin/includesMediaListTable.php
@@ -0,0 +1,50 @@
+<?php
+
+/**
+ * @group admin
+ */
+class Tests_Admin_includesMediaListTable extends WP_UnitTestCase {
+
+	public static function set_up_before_class() {
+		parent::set_up_before_class();
+
+		require_once ABSPATH . 'wp-admin/includes/class-wp-media-list-table.php';
+	}
+
+	/**
+	 * Tests that a call to WP_Media_List_Table::prepare_items() on a site without any scheduled events
+	 * does not result in a PHP warning.
+	 *
+	 * The warning that we should not see:
+	 * PHP 5.6 - 7.4: `Invalid argument supplied for foreach()`.
+	 * PHP 8.0 and higher: `Warning: foreach() argument must be of type array|object, bool given`.
+	 *
+	 * Note: This does not test the actual functioning of the WP_Media_List_Table::prepare_items() method.
+	 * It just and only tests for/against the PHP warning.
+	 *
+	 * @ticket 53949
+	 * @covers WP_Media_List_Table::prepare_items
+	 */
+	public function test_prepare_items_without_cron_option_does_not_throw_warning() {
+		global $wp_query;
+
+		// Note: setMethods() is deprecated in PHPUnit 9, but still supported.
+		$mock = $this->getMockBuilder( WP_Media_List_Table::class )
+			->disableOriginalConstructor()
+			->disallowMockingUnknownTypes()
+			->setMethods( array( 'set_pagination_args' ) )
+			->getMock();
+
+		$mock->expects( $this->once() )
+			->method( 'set_pagination_args' );
+
+		$wp_query->query_vars['posts_per_page'] = 10;
+		delete_option( 'cron' );
+
+		// Verify that the cause of the error is in place.
+		$this->assertFalse( _get_cron_array(), '_get_cron_array() does not return false' );
+
+		// If this test does not error out due to the PHP warning, we're good.
+		$mock->prepare_items();
+	}
+}