AssetManagerTest\Service\CollectionsResolverTest::testTwoCollectionsHasDifferentCacheKey PHP Method

    public function testTwoCollectionsHasDifferentCacheKey()
    {
        $aggregateResolver = $this->getMock(ResolverInterface::class);
        //assets with same 'last modifled time'.
        $now = time();
        $bacon = new Asset\StringAsset('bacon');
        $bacon->setLastModified($now);
        $bacon->mimetype = 'text/plain';
        $eggs = new Asset\StringAsset('eggs');
        $eggs->setLastModified($now);
        $eggs->mimetype = 'text/plain';
        $assets = array(array('bacon', $bacon), array('eggs', $eggs));
        $aggregateResolver->expects($this->any())->method('resolve')->will($this->returnValueMap($assets));
        $resolver = new CollectionResolver(array('collection1' => array('bacon'), 'collection2' => array('eggs')));
        $mimeResolver = new MimeResolver();
        $assetFilterManager = new AssetFilterManager();
        $assetFilterManager->setMimeResolver($mimeResolver);
        $resolver->setAggregateResolver($aggregateResolver);
        $resolver->setAssetFilterManager($assetFilterManager);
        $collection1 = $resolver->resolve('collection1');
        $collection2 = $resolver->resolve('collection2');
        $cacheInterface = $this->getMock(CacheInterface::class);
        $cacheKeys = new \ArrayObject();
        $callback = function ($key) use($cacheKeys) {
            $cacheKeys[] = $key;
            return true;
        };
        $cacheInterface->expects($this->exactly(2))->method('has')->will($this->returnCallback($callback));
        $cacheInterface->expects($this->exactly(2))->method('get')->will($this->returnValue('cached content'));
        $cache1 = new AssetCache($collection1, $cacheInterface);
        $cache1->load();
        $cache2 = new AssetCache($collection2, $cacheInterface);
        $cache2->load();
        $this->assertCount(2, $cacheKeys);
        $this->assertNotEquals($cacheKeys[0], $cacheKeys[1]);
    }