code: def test_single_doc(self):
      with pytest.raises(
          TypeError,
          match="DocumentSplitter expects a List of Documents as input.",
      ):
          splitter = DocumentSplitter()
          splitter.run(documents=Document())
  
file_path: haystack/test/components/preprocessors/test_document_splitter.py
imports: import pytest
  from haystack import Document
  from haystack.components.preprocessors import DocumentSplitter
label_desc: Use image node_id 2 for calling the TestDocumentSplitter obj's underlying member method code with example usage: obj.test_single_doc() without return types