fallback to importlib.resources when __file__ is undefined

tests/test_config.py

@@ -14,12 +14,14 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+import importlib
 from io import StringIO
 import os
 import shutil
 import sys
 import tempfile
 import unittest
+import unittest.mock
 
 from tests.common import build_temp_workspace
 
@@ -475,3 +477,38 @@ class IgnorePathConfigTestCase(unittest.TestCase):
             './s/s/ign-trail/s/s/file2.lint-me-anyway.yaml:4:17: ' + trailing,
             './s/s/ign-trail/s/s/file2.lint-me-anyway.yaml:5:5: ' + hyphen,
         )))
+
+
+class MissingModulePath(unittest.TestCase):
+
+    @classmethod
+    def setUpClass(cls):
+        super(MissingModulePath, cls).setUpClass()
+        cls.mock_module_path = unittest.mock.patch.dict(config.__dict__,
+                                                        {'_MODULE_PATH': None})
+
+    def setUp(self):
+        if 'importlib.resources' in sys.modules:
+            del sys.modules['importlib.resources']
+
+    @unittest.skipIf(sys.version_info < (3, 7),
+                     'importlib.resources not supported')
+    def test_missing_module_path(self):
+        '''When __file__ is undefined, importlib.resources should be used'''
+        with self.mock_module_path:
+            importlib.reload(config)
+            self.assertTrue(config.__dict__['_MODULE_PATH'] is None)
+            self.assertTrue('importlib.resources' in sys.modules.keys())
+            self.assertTrue(config.get_extended_config('default') is not None)
+
+    @unittest.skipIf(sys.version_info < (3, 7),
+                     'importlib.resources not supported')
+    def test_missing_importlib_resources(self):
+        '''When __file__ is undefined and importlib.resources is unavailable,
+        an ImportError exception is expected.'''
+        with self.mock_module_path:
+            sys.modules['importlib.resources'] = None  # force an ImportError
+            error_regex = '.*importlib.resources library is required.*'
+            with self.assertRaisesRegex(ImportError, error_regex):
+                importlib.reload(config)
+            self.assertTrue(config.__dict__['_MODULE_PATH'] is None)

yamllint/config.py

@@ -19,8 +19,35 @@ import os.path
 import pathspec
 import yaml
 
+import yamllint.conf
 import yamllint.rules
 
+try:
+    _MODULE_PATH  # allows unit tests to patch this
+except NameError:
+    try:
+        _MODULE_PATH = __file__
+    except NameError:  # pragma: no cover
+        _MODULE_PATH = None
+
+if _MODULE_PATH is not None:
+    def _get_config(name):
+        module_dir = os.path.dirname(os.path.realpath(_MODULE_PATH))
+        config_path = os.path.join(module_dir, 'conf', name)
+        with open(config_path) as config:
+            return config.read()
+else:
+    try:
+        from importlib.resources import read_text
+    except ImportError as exc:
+        _IMPORT_ERR_MESSAGE = (
+            "The importlib.resources library is required to locate resources "
+            "when __file__ is not defined")
+        raise ImportError(_IMPORT_ERR_MESSAGE) from exc
+
+    def _get_config(name):
+        return read_text(yamllint.conf, name)
+
 
 class YamlLintConfigError(Exception):
     pass
@@ -90,8 +117,8 @@ class YamlLintConfig(object):
 
         # Does this conf override another conf that we need to load?
         if 'extends' in conf:
-            path = get_extended_config_file(conf['extends'])
-            base = YamlLintConfig(file=path)
+            config = get_extended_config(conf['extends'])
+            base = YamlLintConfig(content=config)
             try:
                 self.extend(base)
             except Exception as e:
@@ -200,14 +227,11 @@ def validate_rule_conf(rule, conf):
     return conf
 
 
-def get_extended_config_file(name):
+def get_extended_config(name):
     # Is it a standard conf shipped with yamllint...
     if '/' not in name:
-        std_conf = os.path.join(os.path.dirname(os.path.realpath(__file__)),
-                                'conf', name + '.yaml')
-
-        if os.path.isfile(std_conf):
-            return std_conf
-
+        resource = name + '.yaml'
+        return _get_config(resource)
     # or a custom conf on filesystem?
-    return name
+    with open(name) as config:
+        return config.read()