Extension prefix is limited to lgt/pct/spx/nb

#87 #138 extension for file name with dot is simply the extension, unless the intermediate prefix is one of lgt/pct/spx/nb
Fixes #138

HISTORY.rst

@@ -14,7 +14,8 @@ Release History
 
 **BugFixes**
 
-- Main language of scripts is inferred from script extension. Fixes the round trip conversion on Python notebooks with a javascript cell.
+- Main language of scripts is inferred from script extension. Fixes a round trip conversion issue for Python notebooks with a Javascript cell.
+- Format extension must start with one of ``.lgt``,``.pct``,``.spx`` and ``.nb`` (#87,#138)
 
 0.8.6 (2018-11-29)
 ++++++++++++++++++++++

jupytext/cli.py

@@ -303,6 +303,6 @@ def jupytext(args=None):
                                update=args.update,
                                freeze_metadata=args.freeze_metadata,
                                comment_magics=args.comment_magics)
-    except ValueError as err:  # (ValueError, TypeError, IOError) as err:
+    except (ValueError, TypeError, IOError) as err:
         print('jupytext: error: ' + str(err))
         exit(1)

jupytext/contentsmanager.py

@@ -19,9 +19,8 @@
 
 import jupytext
 from .combine import combine_inputs_with_outputs
-from .formats import check_file_version, NOTEBOOK_EXTENSIONS, \
+from .formats import check_file_version, NOTEBOOK_EXTENSIONS, EXTENSION_PREFIXES, \
     format_name_for_ext, parse_one_format, parse_formats, transition_to_jupytext_section_in_metadata
-from .metadata_filter import metadata_filter_as_dict
 
 
 def kernelspec_from_language(language):
@@ -105,10 +104,10 @@ def file_fmt_ext(path):
     Return file name, format (possibly .nb.py) and extension (.py)
     """
     file, ext = os.path.splitext(path)
-    file, intermediate_ext = os.path.splitext(file)
-    if file and len(intermediate_ext) <= 4:
-        return file, intermediate_ext + ext, ext
-    return file + intermediate_ext, ext, ext
+    file, ext_prefix = os.path.splitext(file)
+    if file and ext_prefix in EXTENSION_PREFIXES:
+        return file, ext_prefix + ext, ext
+    return file + ext_prefix, ext, ext
 
 
 class TextFileContentsManager(FileContentsManager, Configurable):

jupytext/formats.py

@@ -114,6 +114,7 @@ def __init__(self,
 
 NOTEBOOK_EXTENSIONS = list(dict.fromkeys(
     ['.ipynb'] + [fmt.extension for fmt in JUPYTEXT_FORMATS]))
+EXTENSION_PREFIXES = ['.lgt', '.spx', '.pct', '.nb']
 
 
 def get_format(ext, format_name=None):
@@ -260,7 +261,17 @@ def parse_one_format(ext_and_format_name):
     if not ext.startswith('.'):
         ext = '.' + ext
 
-    return ext, format_name
+    legitimate_extensions = NOTEBOOK_EXTENSIONS + ['.auto']
+    if ext in legitimate_extensions:
+        return ext, format_name
+
+    if ext.rfind('.') > 0:
+        pre, short_ext = os.path.splitext(ext)
+        if short_ext in legitimate_extensions and pre in EXTENSION_PREFIXES:
+            return ext, format_name
+
+    raise ValueError("Extension '{}' should have been one of '{}', with optional prefix among '{}'".format(
+        ext, "','".join(legitimate_extensions), "','".join(EXTENSION_PREFIXES)))
 
 
 def parse_formats(formats):

tests/test_cli.py

@@ -102,7 +102,7 @@ def test_error_not_notebook_ext_input(nb_file='notebook.ext'):
 
 
 def test_error_not_notebook_ext_dest1(nb_file=list_notebooks()[0]):
-    with pytest.raises(TypeError):
+    with pytest.raises(ValueError):
         convert_notebook_files([nb_file], fmt='ext')
 
 

tests/test_contentsmanager.py

@@ -394,6 +394,38 @@ def test_save_to_light_percent_sphinx_format(nb_file, tmpdir):
     compare_notebooks(nb, model['content'])
 
 
+@skip_if_dict_is_not_ordered
+@pytest.mark.parametrize('nb_file', list_notebooks('ipynb_py'))
+def test_pair_notebook_with_dot(nb_file, tmpdir):
+    # Reproduce issue #138
+    tmp_py = 'file.5.1.py'
+    tmp_ipynb = 'file.5.1.ipynb'
+
+    cm = jupytext.TextFileContentsManager()
+    cm.root_dir = str(tmpdir)
+
+    nb = jupytext.readf(nb_file)
+    nb['metadata']['jupytext'] = {'formats': 'ipynb,py:percent'}
+
+    # save to ipynb and three python flavors
+    with mock.patch('jupytext.header.INSERT_AND_CHECK_VERSION_NUMBER', True):
+        cm.save(model=dict(type='notebook', content=nb), path=tmp_ipynb)
+
+    assert os.path.isfile(str(tmpdir.join(tmp_ipynb)))
+
+    # read files
+    with open(str(tmpdir.join(tmp_py))) as stream:
+        assert read_format_from_metadata(stream.read(), '.py') == 'percent'
+
+    model = cm.get(path=tmp_py)
+    assert model['name'] == 'file.5.1.py'
+    compare_notebooks(nb, model['content'])
+
+    model = cm.get(path=tmp_ipynb)
+    assert model['name'] == 'file.5.1.ipynb'
+    compare_notebooks(nb, model['content'])
+
+
 @pytest.mark.parametrize('nb_file', list_notebooks('ipynb_py')[:1])
 def test_preferred_format_allows_to_read_others_format(nb_file, tmpdir):
     # 1. write py ipynb
@@ -611,7 +643,7 @@ def test_metadata_filter_is_effective(nb_file, tmpdir):
         cm.save(model=dict(type='notebook', content=nb), path=tmp_ipynb)
 
     # set config
-    cm.default_jupytext_formats = 'ipynb, py'
+    cm.default_jupytext_formats = 'ipynb,py'
     cm.default_notebook_metadata_filter = 'jupytext,-all'
     cm.default_cell_metadata_filter = '-all'