N°2651 rollback gitignore for lib tests dirs

Too dangerous ! We'll work properly on this but for 2.8

lib/symfony/cache/Tests/Simple/RedisClusterCacheTest.php

@@ -0,0 +1,27 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\Cache\Tests\Simple;
+
+class RedisClusterCacheTest extends AbstractRedisCacheTest
+{
+    public static function setUpBeforeClass()
+    {
+        if (!class_exists('RedisCluster')) {
+            self::markTestSkipped('The RedisCluster class is required.');
+        }
+        if (!$hosts = getenv('REDIS_CLUSTER_HOSTS')) {
+            self::markTestSkipped('REDIS_CLUSTER_HOSTS env var is not defined.');
+        }
+
+        self::$redis = new \RedisCluster(null, explode(' ', $hosts));
+    }
+}