code: def test_does_raise_on_split_markdown_cell():
      ref = new_notebook(
          cells=[new_markdown_cell("Cell one\n\n\nsecond line")]
      )
      test = new_notebook(
          cells=[
              new_markdown_cell("Cell one"),
              new_markdown_cell("second line"),
          ]
      )
      with pytest.raises(NotebookDifference):
          compare_notebooks(test, ref, "md")
  
imports: import pytest
  from nbformat.v4.nbbase import new_code_cell, new_markdown_cell, new_notebook, new_raw_cell
  from jupytext.compare import NotebookDifference, compare, compare_cells, compare_notebooks
  from jupytext.compare import test_round_trip_conversion
label_desc: Use image node_id 9 for calling a global function with example usage: test_does_raise_on_split_markdown_cell() without return types