Use TTL for in-memory cache to support long-lived instances

tests/OnlineTests/ObjectRetrieverCacheTest.php

@@ -29,19 +29,26 @@ class ObjectRetrieverCacheTest extends \PHPUnit\Framework\TestCase {
         $this->assertNotNull($cacheStorage->fetch($retriever->getCacheKey((string)$coid)));
         $this->assertStringContainsString('from Core API', $logger->getLastLogMessage());
 
+        // Get from same retriever, assert in-memory-cache
+        $object2 = $retriever->getCloudObject($coid);
+
+        $this->assertNotNull($object1);
+        $this->assertStringContainsString('previous', $logger->getLastLogMessage());
+
         // Reinitialize retriever with same cache storage to verify that cache is used
         $retriever = new ObjectRetriever([
             'cache_storage' => $cacheStorage,
             'logger' => $logger
         ]);
 
-        $object2 = $retriever->getCloudObject($coid);
+        $object3 = $retriever->getCloudObject($coid);
 
         $this->assertNotNull($object2);
         $this->assertNotNull($cacheStorage->fetch($retriever->getCacheKey((string)$coid)));
         $this->assertStringContainsString('from object cache', $logger->getLastLogMessage());
 
         $this->assertEquals($object1->getRevision(), $object2->getRevision());
+        $this->assertEquals($object2->getRevision(), $object3->getRevision());
     }
 
 }