Add basic unit tests

There were none before this. Adding this test exposed a coding error in
the main method (returned None instead of 0)

Change-Id: Ibf6bf8276a96fceebd9f71773209452f786d0ef7

os_refresh_config/os_refresh_config.py

@@ -98,6 +98,7 @@ def main(argv=sys.argv):
 
     lock.truncate(0)
     lock.close()
+    return 0
 
 
 if __name__ == '__main__':

os_refresh_config/tests/test_main.py

@@ -0,0 +1,42 @@
+# Copyright 2014 Hewlett-Packard Development Company, L.P.
+# 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 os
+
+import fixtures
+import testtools
+
+from os_refresh_config import os_refresh_config
+
+
+class TestMain(testtools.TestCase):
+    def setUp(self):
+        super(TestMain, self).setUp()
+        self.useFixture(fixtures.NestedTempfile())
+        td = self.useFixture(fixtures.TempDir())
+        self.useFixture(
+            fixtures.EnvironmentVariable(
+                "OS_REFRESH_CONFIG_BASE_DIR",
+                td.path))
+
+    def _run_main(self, args=[]):
+        self.lockdir = self.useFixture(fixtures.TempDir())
+        self.lockfile = os.path.join(self.lockdir.path, 'lock')
+        return os_refresh_config.main(argv=['os-refresh-config',
+                                      '--lockfile', self.lockfile])
+
+    def test_main(self):
+        self.assertEqual(0, self._run_main())
+        self.assertTrue(os.path.exists(self.lockfile))
+        self.assertEqual(0, len(open(self.lockfile).read()))