=== modified file 'mandos-ctl'
--- mandos-ctl	2019-03-15 19:59:49 +0000
+++ mandos-ctl	2019-03-15 21:59:44 +0000
@@ -93,20 +93,14 @@
     if options.debug:
         log.setLevel(logging.DEBUG)
 
-    try:
-        bus = dbus.SystemBus()
-        log.debug("D-Bus: Connect to: (busname=%r, path=%r)",
-                  dbus_busname, server_dbus_path)
-        mandos_dbus_objc = bus.get_object(dbus_busname,
-                                          server_dbus_path)
-    except dbus.exceptions.DBusException:
-        log.critical("Could not connect to Mandos server")
-        sys.exit(1)
-
-    mandos_serv = dbus.Interface(mandos_dbus_objc,
-                                 dbus_interface=server_dbus_interface)
+    bus = dbus.SystemBus()
+
+    mandos_dbus_object = get_mandos_dbus_object(bus)
+
+    mandos_serv = dbus.Interface(
+        mandos_dbus_object, dbus_interface=server_dbus_interface)
     mandos_serv_object_manager = dbus.Interface(
-        mandos_dbus_objc, dbus_interface=dbus.OBJECT_MANAGER_IFACE)
+        mandos_dbus_object, dbus_interface=dbus.OBJECT_MANAGER_IFACE)
 
     try:
         log.debug("D-Bus: %s:%s:%s.GetManagedObjects()", dbus_busname,
@@ -436,6 +430,19 @@
         options.remove = True
 
 
+def get_mandos_dbus_object(bus):
+    try:
+        log.debug("D-Bus: Connect to: (busname=%r, path=%r)",
+                  dbus_busname, server_dbus_path)
+        mandos_dbus_object = bus.get_object(dbus_busname,
+                                            server_dbus_path)
+    except dbus.exceptions.DBusException:
+        log.critical("Could not connect to Mandos server")
+        sys.exit(1)
+
+    return mandos_dbus_object
+
+
 class SilenceLogger(object):
     "Simple context manager to silence a particular logger"
     def __init__(self, loggername):
@@ -988,6 +995,55 @@
                 self.check_option_syntax(options)
 
 
+class Test_get_mandos_dbus_object(unittest.TestCase):
+    def test_calls_and_returns_get_object_on_bus(self):
+        class MockBus(object):
+            called = False
+            def get_object(mockbus_self, busname, dbus_path):
+                # Note that "self" is still the testcase instance,
+                # this MockBus instance is in "mockbus_self".
+                self.assertEqual(busname, dbus_busname)
+                self.assertEqual(dbus_path, server_dbus_path)
+                mockbus_self.called = True
+                return mockbus_self
+
+        mockbus = get_mandos_dbus_object(bus=MockBus())
+        self.assertIsInstance(mockbus, MockBus)
+        self.assertTrue(mockbus.called)
+
+    def test_logs_and_exits_on_dbus_error(self):
+        class MockBusFailing(object):
+            def get_object(self, busname, dbus_path):
+                raise dbus.exceptions.DBusException("Test")
+
+        # assertLogs only exists in Python 3.4
+        if hasattr(self, "assertLogs"):
+            with self.assertLogs(log, logging.CRITICAL):
+                with self.assertRaises(SystemExit) as e:
+                    bus = get_mandos_dbus_object(bus=MockBus())
+        else:
+            critical_filter = self.CriticalFilter()
+            log.addFilter(critical_filter)
+            try:
+                with self.assertRaises(SystemExit) as e:
+                    get_mandos_dbus_object(bus=MockBusFailing())
+            finally:
+                log.removeFilter(critical_filter)
+            self.assertTrue(critical_filter.found)
+        if isinstance(e.exception.code, int):
+            self.assertNotEqual(e.exception.code, 0)
+        else:
+            self.assertIsNotNone(e.exception.code)
+
+    class CriticalFilter(logging.Filter):
+        """Don't show, but register, critical messages"""
+        found = False
+        def filter(self, record):
+            is_critical = record.levelno >= logging.CRITICAL
+            self.found = is_critical or self.found
+            return not is_critical
+
+
 class Test_SilenceLogger(unittest.TestCase):
     loggername = "mandos-ctl.Test_SilenceLogger"
     log = logging.getLogger(loggername)