Add some useful features to our flags

* No longer dies if there are unknown flags.
* Allows you to declare that you will use a flag from another file
* Allows you to import new flags at runtime and reparses the original
  arguments to fill them once they are accessed.

3 files changed, 104 insertions, 0 deletions

diff --git a/nova/tests/declare_flags.py b/nova/tests/declare_flags.py
new file mode 100644
index 000000000..f7c91f9dd
--- /dev/null
+++ b/nova/tests/declare_flags.py
@@ -0,0 +1,5 @@
+from nova import flags
+
+FLAGS = flags.FLAGS
+
+flags.DEFINE_integer('answer', 42, 'test flag')
diff --git a/nova/tests/flags_unittest.py b/nova/tests/flags_unittest.py
new file mode 100644
index 000000000..44da94d04
--- /dev/null
+++ b/nova/tests/flags_unittest.py
@@ -0,0 +1,94 @@
+# vim: tabstop=4 shiftwidth=4 softtabstop=4
+
+# Copyright 2010 United States Government as represented by the
+# Administrator of the National Aeronautics and Space Administration.
+# All Rights Reserved.
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+import logging
+from twisted.internet import defer
+from twisted.internet import reactor
+from xml.etree import ElementTree
+
+from nova import exception
+from nova import flags
+from nova import process
+from nova import test
+from nova import utils
+
+
+class FlagsTestCase(test.TrialTestCase):
+    def setUp(self):
+        super(FlagsTestCase, self).setUp()
+        self.FLAGS = flags.FlagValues()
+        self.global_FLAGS = flags.FLAGS
+
+    def test_define(self):
+        self.assert_('string' not in self.FLAGS)
+        self.assert_('int' not in self.FLAGS)
+        self.assert_('false' not in self.FLAGS)
+        self.assert_('true' not in self.FLAGS)
+
+        flags.DEFINE_string('string', 'default', 'desc', flag_values=self.FLAGS)
+        flags.DEFINE_integer('int', 1, 'desc', flag_values=self.FLAGS)
+        flags.DEFINE_bool('false', False, 'desc', flag_values=self.FLAGS)
+        flags.DEFINE_bool('true', True, 'desc', flag_values=self.FLAGS)
+
+        self.assert_(self.FLAGS['string'])
+        self.assert_(self.FLAGS['int'])
+        self.assert_(self.FLAGS['false'])
+        self.assert_(self.FLAGS['true'])
+        self.assertEqual(self.FLAGS.string, 'default')
+        self.assertEqual(self.FLAGS.int, 1)
+        self.assertEqual(self.FLAGS.false, False)
+        self.assertEqual(self.FLAGS.true, True)
+
+        argv = ['flags_test',
+                '--string', 'foo',
+                '--int', '2',
+                '--false',
+                '--notrue']
+
+        self.FLAGS(argv)
+        self.assertEqual(self.FLAGS.string, 'foo')
+        self.assertEqual(self.FLAGS.int, 2)
+        self.assertEqual(self.FLAGS.false, True)
+        self.assertEqual(self.FLAGS.true, False)
+
+    def test_declare(self):
+        self.assert_('answer' not in self.global_FLAGS)
+        flags.DECLARE('answer', 'nova.tests.declare_flags')
+        self.assert_('answer' in self.global_FLAGS)
+        self.assertEqual(self.global_FLAGS.answer, 42)
+
+        # Make sure we don't overwrite anything
+        self.global_FLAGS.answer = 256
+        self.assertEqual(self.global_FLAGS.answer, 256)
+        flags.DECLARE('answer', 'nova.tests.declare_flags')
+        self.assertEqual(self.global_FLAGS.answer, 256)
+
+    def test_runtime_and_unknown_flags(self):
+        self.assert_('runtime_answer' not in self.global_FLAGS)
+
+        argv = ['flags_test', '--runtime_answer=60', 'extra_arg']
+        args = self.global_FLAGS(argv)
+        self.assertEqual(len(args), 2)
+        self.assertEqual(args[1], 'extra_arg')
+
+        self.assert_('runtime_answer' not in self.global_FLAGS)
+
+        import nova.tests.runtime_flags
+
+        self.assert_('runtime_answer' in self.global_FLAGS)
+        self.assertEqual(self.global_FLAGS.runtime_answer, 60)
diff --git a/nova/tests/runtime_flags.py b/nova/tests/runtime_flags.py
new file mode 100644
index 000000000..a2cc4738a
--- /dev/null
+++ b/nova/tests/runtime_flags.py
@@ -0,0 +1,5 @@
+from nova import flags
+
+FLAGS = flags.FLAGS
+
+flags.DEFINE_integer('runtime_answer', 54, 'test flag')