code: def test_init_default(self):
      retriever = InMemoryBM25Retriever(InMemoryDocumentStore())
      assert retriever.filters is None
      assert retriever.top_k == 10
      assert retriever.scale_score is False
  
imports: from typing import Dict, Any
  import pytest
  from haystack import Pipeline, DeserializationError
  from haystack.testing.factory import document_store_class
  from haystack.components.retrievers.in_memory import InMemoryBM25Retriever
  from haystack.dataclasses import Document
  from haystack.document_stores.in_memory import InMemoryDocumentStore
label_desc: Use image node_id 1 for calling the TestMemoryBM25Retriever obj's underlying member method code with example usage: obj.test_init_default() without return types