Normalizes non lowercase option group names in conf files

To avoid inconsistency of option group name format used in conf files,
this patch normalizes group names to all lowercase names

Implements bp cfg-lowercase-groups

Change-Id: If8e6c671be776a708a7200e52e4897a8a3b90bdf

oslo/config/cfg.py

@@ -491,6 +491,12 @@ def set_defaults(opts, **kwargs):
             opt.default = kwargs[opt.dest]
 
 
+def _normalize_group_name(group_name):
+    if group_name == 'DEFAULT':
+        return group_name
+    return group_name.lower()
+
+
 class Opt(object):
 
     """Base class for all configuration options.
@@ -1040,7 +1046,7 @@ class ConfigParser(iniparser.BaseParser):
             return super(ConfigParser, self).parse(f)
 
     def new_section(self, section):
-        self.section = section
+        self.section = _normalize_group_name(section)
         self.sections.setdefault(self.section, {})
 
     def assignment(self, key, value):
@@ -1080,6 +1086,8 @@ class MultiConfigParser(object):
 
     def get(self, names, multi=False):
         rvalue = []
+        names = [(_normalize_group_name(section), name)
+                 for section, name in names]
         for sections in self.parsed:
             for section, name in names:
                 if section not in sections:

tests/test_cfg.py

@@ -1299,6 +1299,20 @@ class OptGroupsTestCase(BaseTestCase):
         self.assertTrue(hasattr(self.conf.blaa, 'foo'))
         self.assertEquals(self.conf.blaa.foo, 'bar')
 
+    def test_arg_group_in_config_file_with_capital_name(self):
+        self.conf.register_group(cfg.OptGroup('blaa'))
+        self.conf.register_opt(cfg.StrOpt('foo'), group='blaa')
+
+        paths = self.create_tempfiles([('test',
+                                        '[BLAA]\n'
+                                        'foo = bar\n')])
+
+        self.conf(['--config-file', paths[0]])
+
+        self.assertTrue(hasattr(self.conf, 'blaa'))
+        self.assertTrue(hasattr(self.conf.blaa, 'foo'))
+        self.assertEquals(self.conf.blaa.foo, 'bar')
+
 
 class MappingInterfaceTestCase(BaseTestCase):