Ignore changes in the YAML header in jupytext --test

#414

CHANGELOG.md

@@ -2,7 +2,8 @@
 ------------------
 
 **Fixed**
-- Code cells in the Markdown format can contain triple backticks inside multiline strings (#419) 
+- Code cells in the Markdown format can contain triple backticks inside multiline strings (#419)
+- Changes in the YAML header when running `jupytext --test` on text files are ignored (#414).
 
 1.3.2 (2020-01-08)
 ------------------

jupytext/cli.py

@@ -12,6 +12,7 @@
 from .jupytext import read, reads, write, writes
 from .formats import _VALID_FORMAT_OPTIONS, _BINARY_FORMAT_OPTIONS, check_file_version
 from .formats import long_form_one_format, long_form_multiple_formats, short_form_one_format, check_auto_ext
+from .languages import _SCRIPT_EXTENSIONS
 from .header import recursive_update
 from .paired_paths import paired_paths, base_path, full_path, InconsistentPath
 from .combine import combine_inputs_with_outputs
@@ -415,7 +416,19 @@ def jupytext_single_file(nb_file, args, log):
                     notebook = reads(dest_text, fmt=dest_fmt)
 
                 text = writes(notebook, fmt=fmt)
-                compare(text, org_text)
+
+                if args.test_strict:
+                    compare(text, org_text)
+                else:
+                    # we ignore the YAML header in the comparison #414
+                    comment = _SCRIPT_EXTENSIONS.get(fmt['extension'], {}).get('comment', '')
+                    # white spaces between the comment char and the YAML delimiters are allowed
+                    if comment:
+                        comment = comment + r'\s*'
+                    yaml_header = re.compile(r'^{}---\s*\n.*\n{}---\s*\n'.format(comment, comment),
+                                             re.MULTILINE | re.DOTALL)
+                    compare(re.sub(yaml_header, '', text),
+                            re.sub(yaml_header, '', org_text))
 
         except (NotebookDifference, AssertionError) as err:
             sys.stdout.write('{}: {}'.format(nb_file, str(err)))

tests/test_cli.py

@@ -275,6 +275,32 @@ def test_ipynb_to_py_then_update_test(nb_file, tmpdir):
     jupytext(['--test', '--update', '--to', 'ipynb', tmp_nbpy])
 
 
+def test_test_to_ipynb_ignore_version_number_414(tmpdir, text="""# ---
+# jupyter:
+#   jupytext:
+#     text_representation:
+#       extension: .py
+#       format_name: light
+#       format_version: '1.4'
+#       jupytext_version: 1.1.0
+#   kernelspec:
+#     display_name: Python 3
+#     language: python
+#     name: python3
+# ---
+
+# A short markdown cell
+
+# Followed by a code cell
+2 + 2
+"""):
+    tmp_py = str(tmpdir.join('script.py'))
+    with open(tmp_py, 'w') as fp:
+        fp.write(text)
+
+    assert jupytext(['--test', '--to', 'ipynb', tmp_py]) == 0
+
+
 @pytest.mark.parametrize('nb_file', list_notebooks('ipynb_py'))
 def test_convert_to_percent_format(nb_file, tmpdir):
     tmp_ipynb = str(tmpdir.join('notebook.ipynb'))