commit cd37b4cc098902c6bc2155a7d52073831fff0080
Author: Moshe Weitzman <weitzman@tejasa.com>
Date:   Thu Oct 15 13:47:42 2015 -0400

    Test that entries are permanent.

diff --git a/core/lib/Drupal/Core/Cache/ApcuBackend.php b/core/lib/Drupal/Core/Cache/ApcuBackend.php
index a226386..b64fd71 100644
--- a/core/lib/Drupal/Core/Cache/ApcuBackend.php
+++ b/core/lib/Drupal/Core/Cache/ApcuBackend.php
@@ -68,7 +68,7 @@ public function __construct($bin, $site_prefix, CacheTagsChecksumInterface $chec
    * @return string
    *   The APCu key for the cache item ID.
    */
-  protected function getApcuKey($cid) {
+  public function getApcuKey($cid) {
     return $this->binPrefix . $cid;
   }
 
diff --git a/core/modules/system/src/Tests/Cache/ApcuBackendUnitTest.php b/core/modules/system/src/Tests/Cache/ApcuBackendUnitTest.php
index fcb5577..fafac7e 100644
--- a/core/modules/system/src/Tests/Cache/ApcuBackendUnitTest.php
+++ b/core/modules/system/src/Tests/Cache/ApcuBackendUnitTest.php
@@ -87,6 +87,15 @@ public function testSetGet() {
       return;
     }
     parent::testSetGet();
+
+    // Make sure entries are permanent (i.e. no TTL).
+    $backend = $this->getCacheBackend($this->getTestBin());
+    $key = $backend->getApcuKey('TEST8');
+    foreach (new \APCIterator('user', '/^' . $key . '/') as $item) {
+      $this->assertEqual(0, $item['ttl']);
+      $found = TRUE;
+    }
+    $this->assertTrue($found);
   }
 
   /**