code: def test_unsupported_key_in_metadata(
      notebook_with_unsupported_key_in_metadata, fmt_with_cell_metadata
  ):
      """Notebook metadata that can't be parsed in text notebook cannot go to the text file,
      but it should still remain available in the ipynb file for paired notebooks.
      """
      with pytest.warns(
          UserWarning,
          match="The following metadata cannot be exported to the text notebook",
      ):
          text = jupytext.writes(
              notebook_with_unsupported_key_in_metadata,
              fmt_with_cell_metadata,
          )
      assert "unexpected" not in text
      nb_text = jupytext.reads(text, fmt=fmt_with_cell_metadata)
      nb = combine_inputs_with_outputs(
          nb_text,
          notebook_with_unsupported_key_in_metadata,
          fmt=fmt_with_cell_metadata,
      )
      assert nb.cells[-1].metadata == {"unexpected,key": True}
  
imports: import pytest
  from nbformat.v4.nbbase import new_code_cell, new_markdown_cell
  import jupytext
  from jupytext.cell_metadata import _IGNORE_CELL_METADATA, RMarkdownOptionParsingError, is_valid_metadata_key, metadata_to_rmd_options, metadata_to_text, parse_key_equal_value, parse_rmd_options, rmd_options_to_metadata, text_to_metadata, try_eval_metadata
  from jupytext.combine import combine_inputs_with_outputs
  from jupytext.compare import compare, compare_notebooks
  from jupytext.metadata_filter import filter_metadata
label_desc: Use image node_id 29 for calling a global function with example usage: test_unsupported_key_in_metadata(notebook_with_unsupported_key_in_metadata, fmt_with_cell_metadata) without return types