Ban gevent tests

src/python/grpcio_tests/commands.py

@@ -220,6 +220,9 @@ class TestGevent(setuptools.Command):
         'unit._cython._channel_test.ChannelTest.test_negative_deadline_connectivity',
         # TODO(https://github.com/grpc/grpc/issues/15411) enable this test
         'unit._local_credentials_test.LocalCredentialsTest',
+        # TODO(https://github.com/grpc/grpc/issues/22020) LocalCredentials
+        # aren't supported with custom io managers.
+        'unit._contextvars_propagation_test',
         'testing._time_test.StrictRealTimeTest',
     )
     BANNED_WINDOWS_TESTS = (

src/python/grpcio_tests/tests/unit/_contextvars_propagation_test.py

@@ -51,7 +51,7 @@ class _GenericHandler(grpc.GenericRpcHandler):
 def _server():
     try:
         server = test_common.test_server()
-        target = '[::]:0'
+        target = 'localhost:0'
         port = server.add_insecure_port(target)
         server.add_generic_rpc_handlers((_GenericHandler(),))
         server.start()
@@ -65,21 +65,28 @@ if contextvars_supported():
 
     _EXPECTED_VALUE = 24601
     test_var = contextvars.ContextVar("test_var", default=None)
-    test_var.set(_EXPECTED_VALUE)
+
+    def set_up_expected_context():
+        test_var.set(_EXPECTED_VALUE)
 
     class TestCallCredentials(grpc.AuthMetadataPlugin):
 
         def __init__(self):
             self._recorded_value = None
+            self._invoked = False
 
         def __call__(self, context, callback):
             self._recorded_value = test_var.get()
+            self._invoked = True
             callback((), None)
 
         def assert_called(self, test):
+            test.assertTrue(self._invoked)
             test.assertEqual(_EXPECTED_VALUE, self._recorded_value)
 
 else:
+    def set_up_expected_context():
+        pass
 
     class TestCallCredentials(grpc.AuthMetadataPlugin):
 
@@ -93,6 +100,7 @@ else:
 class ContextVarsPropagationTest(unittest.TestCase):
 
     def test_propagation_to_auth_plugin(self):
+        set_up_expected_context()
         with _server() as port:
             target = "localhost:{}".format(port)
             local_credentials = grpc.local_channel_credentials()