code: def test_unsupported_join_mode(self):
      with pytest.raises(
          ValueError,
          match="DocumentJoiner component does not support 'unsupported_mode' join_mode.",
      ):
          DocumentJoiner(join_mode="unsupported_mode")
  
file_path: haystack/test/components/joiners/test_document_joiner.py
imports: import logging
  import pytest
  from haystack import Document
  from haystack.components.joiners.document_joiner import DocumentJoiner
label_desc: Use image node_id 6 for calling the TestDocumentJoiner obj's underlying member method code with example usage: obj.test_unsupported_join_mode() without return types