Merge "Raise an exception when _oparser is not initialized"

2 files changed, 47 insertions, 3 deletions

diff --git a/oslo/config/cfg.py b/oslo/config/cfg.py
index bf8613a..6aafd30 100644
--- a/oslo/config/cfg.py
+++ b/oslo/config/cfg.py
@@ -288,6 +288,13 @@ class Error(Exception):
         return self.msg
 
 
+class NotInitializedError(Error):
+    """Raised if parser is not initialized yet."""
+
+    def __str__(self):
+        return "call expression on parser has not been invoked"
+
+
 class ArgsAlreadyParsedError(Error):
     """Raised if a CLI opt is registered after parsing."""
 
@@ -1635,7 +1642,7 @@ class ConfigOpts(collections.Mapping):
         removed as a side-effect of this method.
         """
         self._args = None
-        self._oparser = argparse.ArgumentParser()
+        self._oparser = None
         self._namespace = None
         self.unregister_opts(self._config_opts)
         for group in self._groups.values():
@@ -1909,11 +1916,31 @@ class ConfigOpts(collections.Mapping):
         logger.log(lvl, "*" * 80)
 
     def print_usage(self, file=None):
-        """Print the usage message for the current program."""
+        """Print the usage message for the current program.
+
+        This method is for use after all CLI options are known
+        registered using __call__() method. If this method is called
+        before the __call__() is invoked, it throws NotInitializedError
+
+        :param file: the File object (if None, output is on sys.stdout)
+        :raises: NotInitializedError
+        """
+        if not self._oparser:
+            raise NotInitializedError()
         self._oparser.print_usage(file)
 
     def print_help(self, file=None):
-        """Print the help message for the current program."""
+        """Print the help message for the current program.
+
+        This method is for use after all CLI options are known
+        registered using __call__() method. If this method is called
+        before the __call__() is invoked, it throws NotInitializedError
+
+        :param file: the File object (if None, output is on sys.stdout)
+        :raises: NotInitializedError
+        """
+        if not self._oparser:
+            raise NotInitializedError()
         self._oparser.print_help(file)
 
     def _get(self, name, group=None, namespace=None):
diff --git a/tests/test_cfg.py b/tests/test_cfg.py
index 698012a..b75f4bc 100644
--- a/tests/test_cfg.py
+++ b/tests/test_cfg.py
@@ -2831,3 +2831,20 @@ class ChoicesTestCase(BaseTestCase):
 
         self.assertTrue(hasattr(self.conf, 'foo'))
         self.assertEqual(self.conf.foo, 'baaar')
+
+
+class PrintHelpTestCase(utils.BaseTestCase):
+
+    def test_print_help_without_init(self):
+        conf = cfg.ConfigOpts()
+        conf.register_opts([])
+        self.assertRaises(cfg.NotInitializedError,
+                          conf.print_help)
+
+    def test_print_help_with_clear(self):
+        conf = cfg.ConfigOpts()
+        conf.register_opts([])
+        conf([])
+        conf.clear()
+        self.assertRaises(cfg.NotInitializedError,
+                          conf.print_help)