code: def test_returns_empty_list_if_no_documents_are_provided(self):
      ranker = MetaFieldRanker(meta_field="rating")
      output = ranker.run(documents=[])
      docs_after = output["documents"]
      assert docs_after == []
  
imports: import pytest
  import logging
  from haystack import Document
  from haystack.components.rankers.meta_field import MetaFieldRanker
label_desc: Use image node_id 7 for calling the TestMetaFieldRanker obj's underlying member method code with example usage: obj.test_returns_empty_list_if_no_documents_are_provided() without return types