class_docstr: Test InMemoryDocumentStore's specific features
class_docstr_tok: ["Test","InMemoryDocumentStore","'s","specific","features"]
code: def test_write_documents(self, document_store):
      docs = [Document(id="1")]
      assert document_store.write_documents(docs) == 1
      with pytest.raises(DuplicateDocumentError):
          document_store.write_documents(docs)
  
imports: import logging
  from unittest.mock import patch
  import pandas
  import pytest
  from haystack import Document
  from haystack.document_stores.errors import DocumentStoreError, DuplicateDocumentError
  from haystack.document_stores.in_memory import InMemoryDocumentStore
  from haystack.testing.document_store import DocumentStoreBaseTests
label_desc: Use image node_id 5 for calling the TestMemoryDocumentStore obj's underlying member method code with example usage: obj.test_write_documents(document_store) without return types