code: def test_no_files_created_on_no_format(tmpdir):
      tmp_ipynb = "notebook.ipynb"
      tmp_rmd = "notebook.Rmd"
      tmp_py = "notebook.py"
  
      cm = TextFileContentsManager()
      cm.root_dir = str(tmpdir)
      cm.formats = ""
  
      cm.save(
          model=notebook_model(
              new_notebook(nbformat=4, metadata=dict())
          ),
          path=tmp_ipynb,
      )
  
      assert not os.path.isfile(str(tmpdir.join(tmp_py)))
      assert not os.path.isfile(str(tmpdir.join(tmp_rmd)))
  
file_path: jupytext/tests/functional/others/test_save_multiple.py
imports: import os
  import pytest
  from nbformat.v4.nbbase import new_notebook
  from nbformat.validator import NotebookValidationError
  from tornado.web import HTTPError
  import jupytext
  from jupytext.compare import compare_notebooks, notebook_model
  from jupytext.contentsmanager import TextFileContentsManager
label_desc: Use image node_id 4 for calling a global function with example usage: test_no_files_created_on_no_format(tmpdir) without return types