The model timestamp of a paired notebook is the timestamp of the inpu…

…t file (#983)

* Model timestamp is independent of content=True/False

* Add issue links

* Version 1.14.1

* Update changelog date

docs/CHANGELOG.md

@@ -1,6 +1,14 @@
 Jupytext ChangeLog
 ==================
 
+1.14.1 (2022-07-29)
+-------------------
+
+**Fixed**
+- The timestamp of a paired notebook is the timestamp of the most recent paired file. This fixes the warning "File Changed"
+after reloading the notebook in Jupyter ([#978](https://github.com/mwouts/jupytext/issues/978)).
+
+
 1.14.0 (2022-07-03)
 -------------------
 
@@ -16,7 +24,7 @@ override existing paired files anymore ([#969](https://github.com/mwouts/jupytex
 
 **Added**
 - We have added a test `test_pre_commit_hook_sync_with_no_config` that documents how to use the pre-commit hook without
-a configuration file (#967)
+a configuration file ([#967](https://github.com/mwouts/jupytext/issues/967))
 
 1.13.8 (2022-04-04)
 -------------------

jupytext/contentsmanager.py

@@ -232,29 +232,21 @@ def get(
             if not load_alternative_format:
                 return model
 
-            if not content:
-                # Modification time of a paired notebook, in this context - Jupyter is checking timestamp
-                # before saving - is the most recent among all representations #118
+            # We will now read a second file if this is a paired notebooks.
+            if content:
+                nbk = model["content"]
+                formats = nbk.metadata.get("jupytext", {}).get(
+                    "formats"
+                ) or config.default_formats(path)
+                formats = long_form_multiple_formats(
+                    formats, nbk.metadata, auto_ext_requires_language_info=False
+                )
+            else:
                 if path not in self.paired_notebooks:
                     return model
 
-                fmt, formats = self.paired_notebooks.get(path)
-                for alt_path, _ in paired_paths(path, fmt, formats):
-                    if alt_path != path and self.exists(alt_path):
-                        alt_model = self.super.get(alt_path, content=False)
-                        if alt_model["last_modified"] > model["last_modified"]:
-                            model["last_modified"] = alt_model["last_modified"]
-
-                return model
-
-            # We will now read a second file if this is a paired notebooks.
-            nbk = model["content"]
-            formats = nbk.metadata.get("jupytext", {}).get(
-                "formats"
-            ) or config.default_formats(path)
-            formats = long_form_multiple_formats(
-                formats, nbk.metadata, auto_ext_requires_language_info=False
-            )
+                _, formats = self.paired_notebooks.get(path)
+                formats = long_form_multiple_formats(formats)
 
             # Compute paired notebooks from formats
             alt_paths = [(path, fmt)]
@@ -276,7 +268,7 @@ def get(
                     alt_paths = paired_paths(path, fmt, formats)
                     formats = long_form_multiple_formats(formats)
 
-            if len(alt_paths) > 1 and ext == ".ipynb":
+            if content and len(alt_paths) > 1 and ext == ".ipynb":
                 # Apply default options (like saving and reloading would do)
                 jupytext_metadata = model["content"]["metadata"].get("jupytext", {})
                 config.set_default_format_options(jupytext_metadata, read=True)
@@ -309,6 +301,12 @@ def read_one_file(alt_path, alt_fmt):
                 path, fmt, formats, get_timestamp, contents_manager_mode=True
             )
 
+            # Modification time of a paired notebook is the timestamp of inputs #118 #978
+            model["last_modified"] = inputs.timestamp
+
+            if not content:
+                return model
+
             # Before we combine the two files, we make sure we're not overwriting ipynb cells
             # with an outdated text file
             content = None

jupytext/version.py

@@ -1,3 +1,3 @@
 """Jupytext's version number"""
 
-__version__ = "1.14.0"
+__version__ = "1.14.1"

tests/test_contentsmanager.py

@@ -1949,3 +1949,45 @@ def test_config_jupytext_jupyter_fs_meta_manager(tmpdir):
         "script.py",
         "script.ipynb",
     }
+
+
+def test_timestamp_is_correct_after_reload_978(tmp_path, python_notebook):
+    """Here we reproduce the conditions in Issue #978 and make sure no
+    warning is generated"""
+    nb = python_notebook
+    nb.metadata["jupytext"] = {"formats": "ipynb,py:percent"}
+
+    cm = jupytext.TextFileContentsManager()
+    cm.root_dir = str(tmp_path)
+
+    ipynb_file = tmp_path / "nb.ipynb"
+    py_file = tmp_path / "nb.py"
+
+    # 1. Save the paired notebook
+    cm.save(notebook_model(nb), path="nb.ipynb")
+    assert ipynb_file.exists()
+    assert py_file.exists()
+
+    # and reload to get the original timestamp
+    org_model = cm.get("nb.ipynb")
+
+    # 2. Edit the py file
+    time.sleep(0.5)
+    text = py_file.read_text()
+    text = (
+        text
+        + """
+
+# %%
+# A new cell
+2 + 2
+"""
+    )
+
+    py_file.write_text(text)
+
+    # 3. Reload the paired notebook and make sure it has the modified content
+    model = cm.get("nb.ipynb")
+    nb = model["content"]
+    assert "A new cell" in nb.cells[-1].source
+    assert model["last_modified"] > org_model["last_modified"]