Ticket #45875: 45875.diff

src/wp-includes/load.php

@@ -1182 +1182 @@
 }
 
 /**
+ * Determines whether the current request is a WordPress REST request.
+ *
+ * @since 5.1.0
+ *
+ * @return bool True if it's a WordPress REST request, false otherwise.
+ */
+function wp_doing_rest_request() {
+        /**
+         * Filters whether the current request is a WordPress REST request.
+         *
+         * @since 5.1.0
+         *
+         * @param bool $wp_doing_rest_request Whether the current request is a WordPress REST request.
+         */
+        return apply_filters( 'wp_doing_rest_request', defined( 'REST_REQUEST' ) && REST_REQUEST );
+}
+
+/**
  * Check whether variable is a WordPress Error.
  *
  * Returns true if $thing is an object of the WP_Error class.

tests/phpunit/tests/load/doingRestRequest.php

@@ +1 @@
+<?php
+/**
+ * Tests for wp_doing_rest_request().
+ *
+ * @group load.php
+ */
+class Tests_Functions_Doing_Rest_Request extends WP_UnitTestCase {
+
+        /**
+         * Tests if a REST request has been done.
+         */
+        public function test_wp_doing_rest_request() {
+                $this->assertFalse( wp_doing_rest_request() );
+
+                add_filter( 'wp_doing_rest_request', '__return_true' );
+                $this->assertTrue( wp_doing_rest_request() );
+
+                define( 'REST_REQUEST', TRUE );
+
+                $this->assertTrue( wp_doing_rest_request() );
+
+                add_filter( 'wp_doing_rest_request', '__return_false' );
+                $this->assertFalse( wp_doing_rest_request() );
+        }
+}