Fix exception when running with no arguments on Python 3

LP: #1424277

3 files changed, 51 insertions, 0 deletions

diff --git a/ChangeLog b/ChangeLog
index ae9926a9..ff5f2aac 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -38,6 +38,7 @@
  - sysvinit: make cloud-init-local run before network (LP: #1275098)
    [Surojit Pathak]
  - Azure: do not re-set hostname if user has changed it (LP: #1375252)
+ - Fix exception when running with no arguments on Python 3. [Daniel Watkins]
 0.7.6:
  - open 0.7.6
  - Enable vendordata on CloudSigma datasource (LP: #1303986)
diff --git a/bin/cloud-init b/bin/cloud-init
index 50bd929e..1d3e7ee3 100755
--- a/bin/cloud-init
+++ b/bin/cloud-init
@@ -611,6 +611,8 @@ def main():
     # Setup signal handlers before running
     signal_handler.attach_handlers()
 
+    if not hasattr(args, 'action'):
+        parser.error('too few arguments')
     (name, functor) = args.action
     if name in ("modules", "init"):
         functor = status_wrapper
diff --git a/tests/unittests/test_cli.py b/tests/unittests/test_cli.py
new file mode 100644
index 00000000..ba447f87
--- /dev/null
+++ b/tests/unittests/test_cli.py
@@ -0,0 +1,48 @@
+import imp
+import sys
+
+import six
+
+from . import helpers as test_helpers
+
+try:
+    from unittest import mock
+except ImportError:
+    import mock
+
+
+class TestCLI(test_helpers.FilesystemMockingTestCase):
+
+    def setUp(self):
+        super(TestCLI, self).setUp()
+        self.stderr = six.StringIO()
+        self.patchStdoutAndStderr(stderr=self.stderr)
+        self.sys_exit = mock.MagicMock()
+        self.patched_funcs.enter_context(
+            mock.patch.object(sys, 'exit', self.sys_exit))
+
+    def _call_main(self):
+        self.patched_funcs.enter_context(
+            mock.patch.object(sys, 'argv', ['cloud-init']))
+        cli = imp.load_module(
+            'cli', open('bin/cloud-init'), '', ('', 'r', imp.PY_SOURCE))
+        try:
+            return cli.main()
+        except:
+            pass
+
+    def test_no_arguments_shows_usage(self):
+        self._call_main()
+        self.assertIn('usage: cloud-init', self.stderr.getvalue())
+
+    def test_no_arguments_exits_2(self):
+        exit_code = self._call_main()
+        if self.sys_exit.call_count:
+            self.assertEqual(mock.call(2), self.sys_exit.call_args)
+        else:
+            self.assertEqual(2, exit_code)
+
+    def test_no_arguments_shows_error_message(self):
+        self._call_main()
+        self.assertIn('cloud-init: error: too few arguments',
+                      self.stderr.getvalue())