Support i18n messages in config generator

if opt.help is i18n'ed then we land up in trouble since
Message objects do not support addition and a TypeError
gets thrown. So we just use a better way to construct
the string to avoid the TypeError.

Closes-Bug: #1408032
Change-Id: If1feb65c6467f1c8176369f49d128c172c569c66

oslo_config/generator.py

@@ -186,7 +186,11 @@ class _OptFormatter(object):
 
         opt_type = self._TYPE_DESCRIPTIONS.get(type(opt), 'unknown type')
 
-        help_text = u'%s(%s)' % (opt.help + ' ' if opt.help else '', opt_type)
+        if opt.help:
+            help_text = u'%s (%s)' % (opt.help,
+                                      opt_type)
+        else:
+            help_text = u'(%s)' % opt_type
         lines = self._format_help(help_text)
 
         for d in opt.deprecated_opts:

test-requirements.txt

@@ -21,5 +21,8 @@ coverage>=3.6
 sphinx>=1.1.2,!=1.2.0,!=1.3b1,<1.3
 oslosphinx>=2.2.0  # Apache-2.0
 
+# Required only for tests
+oslo.i18n>=1.3.0  # Apache-2.0
+
 # mocking framework
 mock>=1.0

tests/test_generator.py

@@ -23,6 +23,7 @@ import testscenarios
 from oslo.config import cfg
 from oslo.config import fixture as config_fixture
 from oslo.config import generator
+from oslo.i18n import fixture as i18n_fixture
 
 load_tests = testscenarios.load_tests_apply_scenarios
 
@@ -31,6 +32,9 @@ class GeneratorTestCase(base.BaseTestCase):
 
     opts = {
         'foo': cfg.StrOpt('foo', help='foo option'),
+        'foo_i18n_help': cfg.StrOpt('foo_i18n_help',
+                                    help=i18n_fixture.Translation().lazy(
+                                        'this is a lazy message')),
         'bar': cfg.StrOpt('bar', help='bar option'),
         'foo-bar': cfg.StrOpt('foo-bar', help='foobar'),
         'no_help': cfg.StrOpt('no_help'),
@@ -206,6 +210,17 @@ class GeneratorTestCase(base.BaseTestCase):
 
 # foobar (string value)
 #foo_bar = <None>
+''')),
+        ('i18n_help',
+         dict(opts=[('test', [(None, [opts['foo_i18n_help']])])],
+              expected='''[DEFAULT]
+
+#
+# From test
+#
+
+# this is a lazy message (string value)
+#foo_i18n_help = <None>
 ''')),
         ('no_help',
          dict(opts=[('test', [(None, [opts['no_help']])])],