tests: cleanup QubesDB connection on domain remove

If domain got removed during the tests (for example DispVM), vm.close()
wouldn't be called in cleanup and some file descriptors will be
leaked. Add event handler for cleaning this up. Do not use close()
method here, because it is destructive, but the object may still be used
by the test.

qubes/tests/__init__.py

@@ -656,6 +656,16 @@ class SystemTestCase(QubesTestCase):
 
         self.addCleanup(self.cleanup_app)
 
+        self.app.add_handler('domain-delete', self.close_qdb_on_remove)
+
+    def close_qdb_on_remove(self, app, event, vm, **kwargs):
+        # only close QubesDB connection, do not perform other (destructive)
+        # actions of vm.close()
+        if vm._qdb_connection_watch is not None:
+            asyncio.get_event_loop().remove_reader(
+                vm._qdb_connection_watch.watch_fd())
+            vm._qdb_connection_watch.close()
+            vm._qdb_connection_watch = None
 
     def cleanup_app(self):
         self.remove_test_vms()

qubes/tests/integ/dispvm.py

@@ -53,7 +53,6 @@ class TC_04_DispVM(qubes.tests.SystemTestCase):
         self.app.default_dispvm = None
         super(TC_04_DispVM, self).tearDown()
 
-    @unittest.expectedFailure
     def test_002_cleanup(self):
         self.loop.run_until_complete(self.testvm.start())
 
@@ -71,7 +70,6 @@ class TC_04_DispVM(qubes.tests.SystemTestCase):
         self.loop.run_until_complete(asyncio.sleep(1))
         self.assertNotIn(dispvm_name, self.app.domains)
 
-    @unittest.expectedFailure
     def test_003_cleanup_destroyed(self):
         """
         Check if DispVM is properly removed even if it terminated itself (#1660)
@@ -160,11 +158,15 @@ class TC_20_DispVMMixin(object):
                 self.wait_for_window(window_title, show=False)
             finally:
                 p.stdin.close()
+                del p
         finally:
             self.loop.run_until_complete(dispvm.cleanup())
             dispvm_name = dispvm.name
             del dispvm
 
+        # give it a time for shutdown + cleanup
+        self.loop.run_until_complete(asyncio.sleep(2))
+
         self.assertNotIn(dispvm_name, self.app.domains,
                           "DispVM not removed from qubes.xml")