Config: Allow overriding only one option when extending

tests/test_config.py

@@ -0,0 +1,69 @@
+# -*- coding: utf-8 -*-
+# Copyright (C) 2016 Adrien Vergé
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# 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 os
+import unittest
+
+from yamllint import config
+
+
+class ConfigTestCase(unittest.TestCase):
+    def setUp(self):
+        self.base = config.parse_config_from_file(os.path.join(
+            os.path.dirname(os.path.dirname(os.path.realpath(__file__))),
+            'yamllint', 'conf', 'default.yml'))
+
+    def test_extend_config_disable_rule(self):
+        new = config.parse_config('extends: default\n'
+                                  'rules:\n'
+                                  '  trailing-spaces: disable\n')
+
+        base = self.base.copy()
+        del base['trailing-spaces']
+
+        self.assertEqual(sorted(new.keys()), sorted(base.keys()))
+        for rule in new:
+            self.assertEqual(new[rule], base[rule])
+
+    def test_extend_config_override_whole_rule(self):
+        new = config.parse_config('extends: default\n'
+                                  'rules:\n'
+                                  '  empty-lines:\n'
+                                  '    max: 42\n'
+                                  '    max-start: 43\n'
+                                  '    max-end: 44\n')
+
+        base = self.base.copy()
+        base['empty-lines']['max'] = 42
+        base['empty-lines']['max-start'] = 43
+        base['empty-lines']['max-end'] = 44
+
+        self.assertEqual(sorted(new.keys()), sorted(base.keys()))
+        for rule in new:
+            self.assertEqual(new[rule], base[rule])
+
+    def test_extend_config_override_rule_partly(self):
+        new = config.parse_config('extends: default\n'
+                                  'rules:\n'
+                                  '  empty-lines:\n'
+                                  '    max-start: 42\n')
+
+        base = self.base.copy()
+        base['empty-lines']['max-start'] = 42
+
+        self.assertEqual(sorted(new.keys()), sorted(base.keys()))
+        for rule in new:
+            self.assertEqual(new[rule], base[rule])

yamllint/config.py

@@ -46,7 +46,11 @@ def extend_config(content):
         if 'extends' in conf:
             base = parse_config_from_file(get_extended_conf(conf['extends']))
 
-            base.update(conf['rules'])
+            for rule in conf['rules']:
+                if type(conf['rules'][rule]) == dict and rule in base:
+                    base[rule].update(conf['rules'][rule])
+                else:
+                    base[rule] = conf['rules'][rule]
             conf['rules'] = base
 
         return conf