Fix Relay support in check_client_dependencies (#473)

---------

Co-authored-by: EarthlingDavey <15802017+EarthlingDavey@users.noreply.github.com>
Co-authored-by: Chris Reynolds <chris@jazzsequence.com>

README.md

@@ -109,6 +109,7 @@ There's a known issue with WordPress `alloptions` cache design. Specifically, a
 ## Changelog ##
 
 ### 1.4.5-dev ###
+* Support Relay in `check_client_dependencies()` correctly [[#471](https://github.com/pantheon-systems/wp-redis/pull/471)] (props @EarthlingDavey)
 
 ### 1.4.4 (November 27, 2023) ###
 * Updates Pantheon WP Coding Standards to 2.0 [[#445](https://github.com/pantheon-systems/wp-redis/pull/445)]

object-cache.php

@@ -1226,7 +1226,12 @@ protected function _connect_redis() {
 	 *               not with a message describing the issue.
 	 */
 	public function check_client_dependencies() {
-		if ( ! class_exists( 'Redis' ) ) {
+		$class_to_check = 'Redis';
+		if ( defined( 'WP_REDIS_USE_RELAY' ) && WP_REDIS_USE_RELAY ) {
+			$class_to_check = 'Relay\Relay';
+		}
+
+		if ( ! class_exists( $class_to_check ) ) {
 			return 'Warning! PHPRedis extension is unavailable, which is required by WP Redis object cache.';
 		}
 		return true;

readme.txt

@@ -106,6 +106,7 @@ Please report security bugs found in the source code of the WP Redis plugin thro
 == Changelog ==
 
 = 1.4.5-dev =
+* Support Relay in check_client_dependencies() with the WP_REDIS_USE_RELAY constant [[#471](https://github.com/pantheon-systems/wp-redis/pull/471)]
 
 = 1.4.4 (November 27, 2023) =
 * Updates Pantheon WP Coding Standards to 2.0 [[#445](https://github.com/pantheon-systems/wp-redis/pull/445)]