Merge "objectcache: defined some missing methods in MultiWriteBagOStuff"

diff --combined tests/phpunit/includes/libs/objectcache/BagOStuffTest.php
index e9b3d62,b68f150..e6b277b
--- 1/tests/phpunit/includes/libs/objectcache/BagOStuffTest.php
--- 2/tests/phpunit/includes/libs/objectcache/BagOStuffTest.php
+++ b/tests/phpunit/includes/libs/objectcache/BagOStuffTest.php
@@@ -16,7 -16,7 +16,7 @@@ class BagOStuffTest extends MediaWikiTe
                parent::setUp();
  
                // type defined through parameter
 -              if ( $this->getCliArg( 'use-bagostuff' ) ) {
 +              if ( $this->getCliArg( 'use-bagostuff' ) !== null ) {
                        $name = $this->getCliArg( 'use-bagostuff' );
  
                        $this->cache = ObjectCache::newFromId( $name );
@@@ -98,7 -98,13 +98,13 @@@
                        $this->cache->merge( $key, $callback, 5, 1 ),
                        'Non-blocking merge (CAS)'
                );
-               $this->assertEquals( 1, $calls );
+               if ( $this->cache instanceof MultiWriteBagOStuff ) {
+                       $wrapper = \Wikimedia\TestingAccessWrapper::newFromObject( $this->cache );
+                       $n = count( $wrapper->caches );
+               } else {
+                       $n = 1;
+               }
+               $this->assertEquals( $n, $calls );
        }
  
        /**