Neos\Media\Domain\Repository\AssetRepository::findAll PHP Method

    public function findAll(AssetCollection $assetCollection = null)
    {
        $query = $this->createQuery();
        $this->addImageVariantFilterClause($query);
        $this->addAssetCollectionToQueryConstraints($query, $assetCollection);
        return $query->execute();
    }

 /**
  * @test
  */
 public function addTag()
 {
     $asset = $this->buildAssetObject();
     $tag = new Tag('test');
     $this->tagRepository->add($tag);
     $asset->addTag($tag);
     $this->persistenceManager->persistAll();
     $this->persistenceManager->clearState();
     $asset = $this->assetRepository->findAll()->getFirst();
     $this->assertAssetHasTags($asset, ['test']);
 }