diff --git a/js/messages.php b/js/messages.php
index f8e31e2cfa..34b3bc6363 100644
--- a/js/messages.php
+++ b/js/messages.php
@@ -30,11 +30,13 @@ require_once './libraries/js_escape.lib.php';
 
 $buffer = PMA\libraries\OutputBuffering::getInstance();
 $buffer->start();
-register_shutdown_function(
-    function () {
-        echo PMA\libraries\OutputBuffering::getInstance()->getContents();
-    }
-);
+if (!defined('TESTSUITE')) {
+    register_shutdown_function(
+        function () {
+            echo PMA\libraries\OutputBuffering::getInstance()->getContents();
+        }
+    );
+}
 
 $js_messages['strNoDropDatabases'] = __('"DROP DATABASE" statements are disabled.');
 if ($cfg['AllowUserDropDatabase']) {
diff --git a/test/libraries/Files_test.php b/test/libraries/Files_test.php
index 6129171dc9..88c28fe449 100644
--- a/test/libraries/Files_test.php
+++ b/test/libraries/Files_test.php
@@ -31,15 +31,17 @@ class FilesTest extends PHPUnit_Framework_TestCase
 
     public function testJsMessages()
     {
-        ob_start();
         $GLOBALS['pmaThemeImage'] = '';
         $cfg = array(
             'AllowUserDropDatabase' => true,
             'GridEditing' => 'click',
+            'OBGzip' => false,
+            'ServerDefault' => 1,
         );
+        $GLOBALS['cfg'] = $cfg;
         require 'js/messages.php';
-        $out = ob_get_contents();
-        ob_end_clean();
+        $buffer->stop();
+        $out = $buffer->getContents();
         $this->assertContains('var PMA_messages = new Array();', $out);
     }