public function testIndexesCreation()
{
$collection = $this->getGridFS();
$id = $collection->storeBytes('abcd', ['foo' => 'bar', 'chunkSize' => 2]);
$newChunksCollection = $this->getCheckDatabase()->selectCollection('fs.chunks');
$indexes = iterator_to_array($newChunksCollection->listIndexes());
$this->assertCount(2, $indexes);
$index = $indexes[1];
$this->assertSame(['files_id' => 1, 'n' => 1], $index->getKey());
$this->assertTrue($index->isUnique());
}