Try to reproduce #900 with a test

tests/test_pre_commit_1_sync_with_config.py

@@ -0,0 +1,106 @@
+import pytest
+from git.exc import HookExecutionError
+from nbformat.v4.nbbase import new_markdown_cell
+from pre_commit.main import main as pre_commit
+
+from jupytext import read, write, TextFileContentsManager
+
+from .utils import (
+    skip_pre_commit_tests_on_windows,
+    skip_pre_commit_tests_when_jupytext_folder_is_not_a_git_repo,
+)
+
+
+@skip_pre_commit_tests_on_windows
+@skip_pre_commit_tests_when_jupytext_folder_is_not_a_git_repo
+def test_pre_commit_hook_sync_with_config(
+    tmpdir,
+    cwd_tmpdir,
+    tmp_repo,
+    jupytext_repo_root,
+    jupytext_repo_rev,
+    python_notebook,
+):
+    pre_commit_config_yaml = f"""
+repos:
+- repo: {jupytext_repo_root}
+  rev: {jupytext_repo_rev}
+  hooks:
+  - id: jupytext
+    args: [--sync]
+"""
+    tmpdir.join(".pre-commit-config.yaml").write(pre_commit_config_yaml)
+
+    tmp_repo.git.add(".pre-commit-config.yaml")
+    pre_commit(["install", "--install-hooks", "-f"])
+
+    tmpdir.join('.jupytext.toml').write('formats = "ipynb,py:percent"\n')
+
+    # create a test notebook and save it in Jupyter
+    nb = python_notebook
+    cm = TextFileContentsManager()
+    cm.root_dir = str(tmpdir)
+    cm.save(dict(type='notebook', content=nb), "test.ipynb")
+
+    # Assert that "text_representation" is in the Jupytext metadata #900
+    assert "text_representation" in tmpdir.join('test.py').read()
+
+    # try to commit it, should fail as the py version hasn't been added
+    tmp_repo.git.add("test.ipynb")
+    with pytest.raises(
+        HookExecutionError,
+        match="git add test.py",
+    ):
+        tmp_repo.index.commit("failing")
+
+    # add the py file, now the commit will succeed
+    tmp_repo.git.add("test.py")
+    tmp_repo.index.commit("passing")
+    assert "test.ipynb" in tmp_repo.tree()
+    assert "test.py" in tmp_repo.tree()
+
+    # The text representation metadata is still there
+    assert "text_representation" in tmpdir.join('test.py').read()
+
+    # modify the ipynb file in another editor
+    nb = read("test.ipynb")
+    nb.cells.append(new_markdown_cell("A new cell"))
+    write(nb, "test.ipynb")
+
+    tmp_repo.git.add("test.ipynb")
+
+    # We try to commit one more time, this updates the py file
+    with pytest.raises(
+        HookExecutionError,
+        match="files were modified by this hook",
+    ):
+        tmp_repo.index.commit("failing")
+
+    # the text file has been updated
+    assert "A new cell" in tmpdir.join("test.py").read()
+
+    # trying to commit should fail again because we forgot to add the .py version
+    with pytest.raises(HookExecutionError, match="git add test.py"):
+        tmp_repo.index.commit("still failing")
+
+    nb = read("test.ipynb")
+    assert len(nb.cells) == 2
+
+    # add the text file, now the commit will succeed
+    tmp_repo.git.add("test.py")
+    tmp_repo.index.commit("passing")
+
+    # modify the .py file
+    nb.cells.append(new_markdown_cell("A third cell"))
+    write(nb, "test.py", fmt="py:percent")
+    tmp_repo.git.add("test.py")
+
+    # the pre-commit hook will update the .ipynb file
+    with pytest.raises(HookExecutionError, match="git add test.ipynb"):
+        tmp_repo.index.commit("failing")
+
+    tmp_repo.git.add("test.ipynb")
+    tmp_repo.index.commit("passing")
+
+    nb = read("test.ipynb")
+    assert len(nb.cells) == 3