Only update the timestamp (not the content) of the text input file

mwouts · Jan 19, 2021 · 22d6961 · 22d6961
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commit 22d6961
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Showing 3 changed files with 14 additions and 9 deletions.
diff --git a/docs/CHANGELOG.md b/docs/CHANGELOG.md
@@ -5,13 +5,14 @@ Jupytext ChangeLog
 ---------------
 
 **Changed**
-- Jupytext does not work properly with the new cell ids of the version 4.5 of `nbformat>=5.1.0` yet, so we added the requirement `nbformat<=5.0.8` (#715)
+- Jupytext does not work properly with the new cell ids of the version 4.5 of `nbformat>=5.1.0` yet, so we added the requirement `nbformat<=5.0.8` ([#715](https://github.com/mwouts/jupytext/issues/715))
+- `jupytext --sync` only updates the timestamp of the text file (not the file itself) when that file is the most recent ([#698](https://github.com/mwouts/jupytext/issues/698))
 
 **Fixed**
-- Indented magic commands are supported (#694)
+- Indented magic commands are supported ([#694](https://github.com/mwouts/jupytext/issues/694))
 
 **Added**
-- Added a test that ensures that `py:percent` scripts end with exactly one blank line (#682)
+- Added a test that ensures that `py:percent` scripts end with exactly one blank line ([#682](https://github.com/mwouts/jupytext/issues/682))
 
 
 1.9.1 (2021-01-06)

diff --git a/jupytext/cli.py b/jupytext/cli.py
@@ -689,10 +689,15 @@ def jupytext_single_file(nb_file, args, log):
             inputs_nb_file = outputs_nb_file = None
 
         def write_function(path, fmt):
-            # Do not write the ipynb file if it was not modified
-            # But, always write text representations to make sure they are the most recent
-            if path == inputs_nb_file and path == outputs_nb_file:
+            if path == inputs_nb_file:
+                # We update the timestamp of the text file to make sure it remains more recent than the ipynb
+                if path != outputs_nb_file:
+                    log("[jupytext] Sync timestamp of '{}'".format(nb_file))
+                    os.utime(nb_file, None)
+
+                # We don't write the ipynb file if it was not modified
                 return
+
             log("[jupytext] Updating '{}'".format(path))
             write(notebook, path, fmt=fmt)
             if args.pre_commit:

diff --git a/tests/test_metadata_filter.py b/tests/test_metadata_filter.py
@@ -156,12 +156,11 @@ def test_default_config_has_priority_over_current_metadata(
 
     cfg_file = tmpdir.join("jupytext.toml")
     cfg_file.write(
-        """default_jupytext_formats = "ipynb,py:percent"
-default_cell_metadata_filter = "-some_metadata_key"
+        """default_cell_metadata_filter = "-some_metadata_key"
 """
     )
 
-    jupytext_cli([str(py_file), "--sync"])
+    jupytext_cli([str(py_file), "--to", "py"])
     assert (
         py_file.read()
         == """# %%