diff --git a/tests/apps.php b/tests/apps.php
index f8bb86ff57c7b..cd173fff5d5e9 100644
--- a/tests/apps.php
+++ b/tests/apps.php
@@ -6,34 +6,34 @@
  * See the COPYING-README file.
  */
 
-function loadDirectory($path) {
+function loadDirectory($path): void {
 	if (strpos($path, 'integration')) {
 		return;
 	}
-	
+
 	if (strpos($path, 'Integration')) {
 		return;
 	}
-	
+
 	if (! $dh = opendir($path)) {
 		return;
 	}
-	
+
 	while ($name = readdir($dh)) {
 		if ($name[0] === '.') {
 			continue;
 		}
-		
+
 		$file = $path . '/' . $name;
 		if (is_dir($file)) {
 			loadDirectory($file);
-		} elseif (substr($name, -4, 4) === '.php') {
+		} elseif (str_ends_with($name, '.php')) {
 			require_once $file;
 		}
 	}
 }
 
-function getSubclasses($parentClassName) {
+function getSubclasses($parentClassName): array {
 	$classes = [];
 	foreach (get_declared_classes() as $className) {
 		if (is_subclass_of($className, $parentClassName)) {