code: def test_linear_score(self):
      ranker = MetaFieldRanker(
          meta_field="rating", ranking_mode="linear_score", weight=0.5
      )
      docs_before = [
          Document(content="abc", meta={"rating": 1.3}, score=0.3),
          Document(content="abc", meta={"rating": 0.7}, score=0.4),
          Document(content="abc", meta={"rating": 2.1}, score=0.6),
      ]
      output = ranker.run(documents=docs_before)
      docs_after = output["documents"]
      assert docs_after[0].score == 0.8
  
imports: import pytest
  import logging
  from haystack import Document
  from haystack.components.rankers.meta_field import MetaFieldRanker
label_desc: Use image node_id 15 for calling the TestMetaFieldRanker obj's underlying member method code with example usage: obj.test_linear_score() without return types