qubes/tests: convert some tearDown into addCleanup

This is because .tearDown() is not executed if the exception occurs in
setUp() [for example self.skipTest() raises an exception]. The lower
levels of .tearDown() being executed are critical to not leaking file
descriptors.

qubes/tests/__init__.py

@@ -345,12 +345,6 @@ class substitute_entry_points(object):
         self._orig_iter_entry_points = None
 
 
-class BeforeCleanExit(BaseException):
-    '''Raised from :py:meth:`QubesTestCase.tearDown` when
-    :py:attr:`qubes.tests.run.QubesDNCTestResult.do_not_clean` is set.'''
-    pass
-
-
 class QubesTestCase(unittest.TestCase):
     '''Base class for Qubes unit tests.
     '''
@@ -379,27 +373,15 @@ class QubesTestCase(unittest.TestCase):
         super().setUp()
         self.loop = asyncio.new_event_loop()
         asyncio.set_event_loop(self.loop)
+        self.addCleanup(self.cleanup_loop)
 
-    def tearDown(self):
+    def cleanup_loop(self):
         # The loop, when closing, throws a warning if there is
         # some unfinished bussiness. Let's catch that.
         with warnings.catch_warnings():
             warnings.simplefilter('error')
             self.loop.close()
-
-        # TODO: find better way in py3
-        try:
-            result = self._outcome.result
-        except:
-            result = self._resultForDoCleanups
-        failed_test_cases = result.failures \
-            + result.errors \
-            + [(tc, None) for tc in result.unexpectedSuccesses]
-
-        if getattr(result, 'do_not_clean', False) \
-                and any(tc is self for tc, exc in failed_test_cases):
-            raise BeforeCleanExit()
-
+        del self.loop
 
     def assertNotRaises(self, excClass, callableObj=None, *args, **kwargs):
         """Fail if an exception of class excClass is raised
@@ -628,10 +610,12 @@ class SystemTestCase(QubesTestCase):
                 qubes.api.internal.QubesInternalAPI,
                 app=self.app, debug=True))
 
-    def tearDown(self):
+        self.addCleanup(self.cleanup_app)
+
+
+    def cleanup_app(self):
         self.remove_test_vms()
 
-        # close the servers before super(), because that might close the loop
         server = None
         for server in self.qubesd:
             for sock in server.sockets:
@@ -674,7 +658,6 @@ class SystemTestCase(QubesTestCase):
                 'libvirt event impl not clean: callbacks %r descriptors %r',
                 self.libvirt_event_impl.callbacks,
                 self.libvirt_event_impl.descriptors)
-        super(SystemTestCase, self).tearDown()
 
     def init_default_template(self, template=None):
         if template is None:

qubes/tests/run.py

@@ -231,10 +231,6 @@ class QubesTestResult(unittest.TestResult):
             self.stream.writeln('%s' % err)
 
 
-class QubesDNCTestResult(QubesTestResult):
-    do_not_clean = True
-
-
 def demo(verbosity=2):
     class TC_00_Demo(qubes.tests.QubesTestCase):
         '''Demo class'''
@@ -293,13 +289,6 @@ parser.add_argument('--no-failfast',
     action='store_false', dest='failfast',
     help='disable --failfast')
 
-parser.add_argument('--do-not-clean', '--dnc', '-D',
-    action='store_true', dest='do_not_clean',
-    help='do not execute tearDown on failed tests. Implies --failfast.')
-parser.add_argument('--do-clean', '-C',
-    action='store_false', dest='do_not_clean',
-    help='do execute tearDown even on failed tests.')
-
 # pylint: disable=protected-access
 try:
     name_to_level = logging._nameToLevel
@@ -387,9 +376,6 @@ def main(args=None):
             print(str(test)) # pylint: disable=superfluous-parens
         return True
 
-    if args.do_not_clean:
-        args.failfast = True
-
     logging.root.setLevel(args.loglevel)
 
     if args.logfile is not None:
@@ -425,10 +411,7 @@ def main(args=None):
         verbosity=(args.verbose-args.quiet),
         failfast=args.failfast)
     unittest.signals.installHandler()
-
-    runner.resultclass = QubesDNCTestResult \
-        if args.do_not_clean else QubesTestResult
-
+    runner.resultclass = QubesTestResult
     result = runner.run(suite)
 
     if args.break_to_repl: