specify metaclasses in a py3-compatible way

8 files changed, 42 insertions, 55 deletions

diff --git a/src/python/grpcio/tests/unit/framework/interfaces/base/_control.py b/src/python/grpcio/tests/unit/framework/interfaces/base/_control.py
index 38102b198a..fe69e63995 100644
--- a/src/python/grpcio/tests/unit/framework/interfaces/base/_control.py
+++ b/src/python/grpcio/tests/unit/framework/interfaces/base/_control.py
@@ -1,4 +1,4 @@
-# Copyright 2015, Google Inc.
+# Copyright 2015-2016, Google Inc.
 # All rights reserved.
 #
 # Redistribution and use in source and binary forms, with or without
@@ -36,6 +36,8 @@ import random  # pylint: disable=unused-import
 import threading
 import time
 
+import six
+
 from grpc.framework.interfaces.base import base
 from tests.unit.framework.common import test_constants
 from tests.unit.framework.interfaces.base import _sequence
@@ -247,8 +249,7 @@ class Instruction(
     CONCLUDE = 'CONCLUDE'
 
 
-class Controller(object):
-  __metaclass__ = abc.ABCMeta
+class Controller(six.with_metaclass(abc.ABCMeta)):
 
   @abc.abstractmethod
   def failed(self, message):
@@ -308,8 +309,7 @@ class Controller(object):
     raise NotImplementedError()
 
 
-class ControllerCreator(object):
-  __metaclass__ = abc.ABCMeta
+class ControllerCreator(six.with_metaclass(abc.ABCMeta)):
 
   @abc.abstractmethod
   def name(self):
diff --git a/src/python/grpcio/tests/unit/framework/interfaces/base/test_interfaces.py b/src/python/grpcio/tests/unit/framework/interfaces/base/test_interfaces.py
index 84afd24d47..0594cfeb31 100644
--- a/src/python/grpcio/tests/unit/framework/interfaces/base/test_interfaces.py
+++ b/src/python/grpcio/tests/unit/framework/interfaces/base/test_interfaces.py
@@ -1,4 +1,4 @@
-# Copyright 2015, Google Inc.
+# Copyright 2015-2016, Google Inc.
 # All rights reserved.
 #
 # Redistribution and use in source and binary forms, with or without
@@ -31,12 +31,13 @@
 
 import abc
 
+import six
+
 from grpc.framework.interfaces.base import base  # pylint: disable=unused-import
 
 
-class Serialization(object):
+class Serialization(six.with_metaclass(abc.ABCMeta)):
   """Specifies serialization and deserialization of test payloads."""
-  __metaclass__ = abc.ABCMeta
 
   def serialize_request(self, request):
     """Serializes a request value used in a test.
@@ -85,9 +86,8 @@ class Serialization(object):
     raise NotImplementedError()
 
 
-class Implementation(object):
+class Implementation(six.with_metaclass(abc.ABCMeta)):
   """Specifies an implementation of the Base layer."""
-  __metaclass__ = abc.ABCMeta
 
   @abc.abstractmethod
   def instantiate(self, serializations, servicer):
diff --git a/src/python/grpcio/tests/unit/framework/interfaces/face/_blocking_invocation_inline_service.py b/src/python/grpcio/tests/unit/framework/interfaces/face/_blocking_invocation_inline_service.py
index c8a3a1bc74..a47fcd3681 100644
--- a/src/python/grpcio/tests/unit/framework/interfaces/face/_blocking_invocation_inline_service.py
+++ b/src/python/grpcio/tests/unit/framework/interfaces/face/_blocking_invocation_inline_service.py
@@ -34,6 +34,8 @@ import itertools
 import unittest
 from concurrent import futures
 
+import six
+
 # test_interfaces is referenced from specification in this module.
 from grpc.framework.foundation import logging_pool
 from grpc.framework.interfaces.face import face
@@ -46,14 +48,13 @@ from tests.unit.framework.interfaces.face import _stock_service
 from tests.unit.framework.interfaces.face import test_interfaces  # pylint: disable=unused-import
 
 
-class TestCase(test_coverage.Coverage, unittest.TestCase):
+class TestCase(six.with_metaclass(abc.ABCMeta, test_coverage.Coverage, unittest.TestCase)):
   """A test of the Face layer of RPC Framework.
 
   Concrete subclasses must have an "implementation" attribute of type
   test_interfaces.Implementation and an "invoker_constructor" attribute of type
   _invocation.InvokerConstructor.
   """
-  __metaclass__ = abc.ABCMeta
 
   NAME = 'BlockingInvocationInlineServiceTest'
 
diff --git a/src/python/grpcio/tests/unit/framework/interfaces/face/_future_invocation_asynchronous_event_service.py b/src/python/grpcio/tests/unit/framework/interfaces/face/_future_invocation_asynchronous_event_service.py
index 1d36a931e8..fb4bee6f86 100644
--- a/src/python/grpcio/tests/unit/framework/interfaces/face/_future_invocation_asynchronous_event_service.py
+++ b/src/python/grpcio/tests/unit/framework/interfaces/face/_future_invocation_asynchronous_event_service.py
@@ -36,6 +36,8 @@ import threading
 import unittest
 from concurrent import futures
 
+import six
+
 # test_interfaces is referenced from specification in this module.
 from grpc.framework.foundation import logging_pool
 from grpc.framework.interfaces.face import face
@@ -104,14 +106,13 @@ class _Callback(object):
           self._condition.wait()
 
 
-class TestCase(test_coverage.Coverage, unittest.TestCase):
+class TestCase(six.with_metaclass(abc.ABCMeta, test_coverage.Coverage, unittest.TestCase)):
   """A test of the Face layer of RPC Framework.
 
   Concrete subclasses must have an "implementation" attribute of type
   test_interfaces.Implementation and an "invoker_constructor" attribute of type
   _invocation.InvokerConstructor.
   """
-  __metaclass__ = abc.ABCMeta
 
   NAME = 'FutureInvocationAsynchronousEventServiceTest'
 
diff --git a/src/python/grpcio/tests/unit/framework/interfaces/face/_invocation.py b/src/python/grpcio/tests/unit/framework/interfaces/face/_invocation.py
index 448e845a08..ff38dc2ece 100644
--- a/src/python/grpcio/tests/unit/framework/interfaces/face/_invocation.py
+++ b/src/python/grpcio/tests/unit/framework/interfaces/face/_invocation.py
@@ -1,4 +1,4 @@
-# Copyright 2015, Google Inc.
+# Copyright 2015-2016, Google Inc.
 # All rights reserved.
 #
 # Redistribution and use in source and binary forms, with or without
@@ -31,6 +31,8 @@
 
 import abc
 
+import six
+
 from grpc.framework.common import cardinality
 
 _CARDINALITY_TO_GENERIC_BLOCKING_BEHAVIOR = {
@@ -62,9 +64,8 @@ _CARDINALITY_TO_MULTI_CALLABLE_ATTRIBUTE = {
 }
 
 
-class Invoker(object):
+class Invoker(six.with_metaclass(abc.ABCMeta)):
   """A type used to invoke test RPCs."""
-  __metaclass__ = abc.ABCMeta
 
   @abc.abstractmethod
   def blocking(self, group, name):
@@ -82,9 +83,8 @@ class Invoker(object):
     raise NotImplementedError()
 
 
-class InvokerConstructor(object):
+class InvokerConstructor(six.with_metaclass(abc.ABCMeta)):
   """A type used to create Invokers."""
-  __metaclass__ = abc.ABCMeta
 
   @abc.abstractmethod
   def name(self):
diff --git a/src/python/grpcio/tests/unit/framework/interfaces/face/_service.py b/src/python/grpcio/tests/unit/framework/interfaces/face/_service.py
index 28941e2ad0..bec8d5113c 100644
--- a/src/python/grpcio/tests/unit/framework/interfaces/face/_service.py
+++ b/src/python/grpcio/tests/unit/framework/interfaces/face/_service.py
@@ -1,4 +1,4 @@
-# Copyright 2015, Google Inc.
+# Copyright 2015-2016, Google Inc.
 # All rights reserved.
 #
 # Redistribution and use in source and binary forms, with or without
@@ -31,16 +31,16 @@
 
 import abc
 
+import six
+
 # face is referenced from specification in this module.
 from grpc.framework.interfaces.face import face  # pylint: disable=unused-import
 from tests.unit.framework.interfaces.face import test_interfaces
 
 
-class UnaryUnaryTestMethodImplementation(test_interfaces.Method):
+class UnaryUnaryTestMethodImplementation(six.with_metaclass(abc.ABCMeta, test_interfaces.Method)):
   """A controllable implementation of a unary-unary method."""
 
-  __metaclass__ = abc.ABCMeta
-
   @abc.abstractmethod
   def service(self, request, response_callback, context, control):
     """Services an RPC that accepts one message and produces one message.
@@ -59,11 +59,9 @@ class UnaryUnaryTestMethodImplementation(test_interfaces.Method):
     raise NotImplementedError()
 
 
-class UnaryUnaryTestMessages(object):
+class UnaryUnaryTestMessages(six.with_metaclass(abc.ABCMeta)):
   """A type for unary-request-unary-response message pairings."""
 
-  __metaclass__ = abc.ABCMeta
-
   @abc.abstractmethod
   def request(self):
     """Affords a request message.
@@ -93,11 +91,9 @@ class UnaryUnaryTestMessages(object):
     raise NotImplementedError()
 
 
-class UnaryStreamTestMethodImplementation(test_interfaces.Method):
+class UnaryStreamTestMethodImplementation(six.with_metaclass(abc.ABCMeta, test_interfaces.Method)):
   """A controllable implementation of a unary-stream method."""
 
-  __metaclass__ = abc.ABCMeta
-
   @abc.abstractmethod
   def service(self, request, response_consumer, context, control):
     """Services an RPC that takes one message and produces a stream of messages.
@@ -116,11 +112,9 @@ class UnaryStreamTestMethodImplementation(test_interfaces.Method):
     raise NotImplementedError()
 
 
-class UnaryStreamTestMessages(object):
+class UnaryStreamTestMessages(six.with_metaclass(abc.ABCMeta)):
   """A type for unary-request-stream-response message pairings."""
 
-  __metaclass__ = abc.ABCMeta
-
   @abc.abstractmethod
   def request(self):
     """Affords a request message.
@@ -150,11 +144,9 @@ class UnaryStreamTestMessages(object):
     raise NotImplementedError()
 
 
-class StreamUnaryTestMethodImplementation(test_interfaces.Method):
+class StreamUnaryTestMethodImplementation(six.with_metaclass(abc.ABCMeta, test_interfaces.Method)):
   """A controllable implementation of a stream-unary method."""
 
-  __metaclass__ = abc.ABCMeta
-
   @abc.abstractmethod
   def service(self, response_callback, context, control):
     """Services an RPC that takes a stream of messages and produces one message.
@@ -180,11 +172,9 @@ class StreamUnaryTestMethodImplementation(test_interfaces.Method):
     raise NotImplementedError()
 
 
-class StreamUnaryTestMessages(object):
+class StreamUnaryTestMessages(six.with_metaclass(abc.ABCMeta)):
   """A type for stream-request-unary-response message pairings."""
 
-  __metaclass__ = abc.ABCMeta
-
   @abc.abstractmethod
   def requests(self):
     """Affords a sequence of request messages.
@@ -214,11 +204,9 @@ class StreamUnaryTestMessages(object):
     raise NotImplementedError()
 
 
-class StreamStreamTestMethodImplementation(test_interfaces.Method):
+class StreamStreamTestMethodImplementation(six.with_metaclass(abc.ABCMeta, test_interfaces.Method)):
   """A controllable implementation of a stream-stream method."""
 
-  __metaclass__ = abc.ABCMeta
-
   @abc.abstractmethod
   def service(self, response_consumer, context, control):
     """Services an RPC that accepts and produces streams of messages.
@@ -244,11 +232,9 @@ class StreamStreamTestMethodImplementation(test_interfaces.Method):
     raise NotImplementedError()
 
 
-class StreamStreamTestMessages(object):
+class StreamStreamTestMessages(six.with_metaclass(abc.ABCMeta)):
   """A type for stream-request-stream-response message pairings."""
 
-  __metaclass__ = abc.ABCMeta
-
   @abc.abstractmethod
   def requests(self):
     """Affords a sequence of request messages.
@@ -278,11 +264,9 @@ class StreamStreamTestMessages(object):
     raise NotImplementedError()
 
 
-class TestService(object):
+class TestService(six.with_metaclass(abc.ABCMeta)):
   """A specification of implemented methods to use in tests."""
 
-  __metaclass__ = abc.ABCMeta
-
   @abc.abstractmethod
   def unary_unary_scenarios(self):
     """Affords unary-request-unary-response test methods and their messages.
diff --git a/src/python/grpcio/tests/unit/framework/interfaces/face/test_interfaces.py b/src/python/grpcio/tests/unit/framework/interfaces/face/test_interfaces.py
index b2b5c10fa6..a5e28b7942 100644
--- a/src/python/grpcio/tests/unit/framework/interfaces/face/test_interfaces.py
+++ b/src/python/grpcio/tests/unit/framework/interfaces/face/test_interfaces.py
@@ -1,4 +1,4 @@
-# Copyright 2015, Google Inc.
+# Copyright 2015-2016, Google Inc.
 # All rights reserved.
 #
 # Redistribution and use in source and binary forms, with or without
@@ -31,13 +31,14 @@
 
 import abc
 
+import six
+
 from grpc.framework.common import cardinality  # pylint: disable=unused-import
 from grpc.framework.interfaces.face import face  # pylint: disable=unused-import
 
 
-class Method(object):
+class Method(six.with_metaclass(abc.ABCMeta)):
   """Specifies a method to be used in tests."""
-  __metaclass__ = abc.ABCMeta
 
   @abc.abstractmethod
   def group(self):
@@ -126,9 +127,8 @@ class Method(object):
     raise NotImplementedError()
 
 
-class Implementation(object):
+class Implementation(six.with_metaclass(abc.ABCMeta)):
   """Specifies an implementation of the Face layer."""
-  __metaclass__ = abc.ABCMeta
 
   @abc.abstractmethod
   def instantiate(
diff --git a/src/python/grpcio/tests/unit/framework/interfaces/links/test_cases.py b/src/python/grpcio/tests/unit/framework/interfaces/links/test_cases.py
index dace6c23f3..2283e79f0a 100644
--- a/src/python/grpcio/tests/unit/framework/interfaces/links/test_cases.py
+++ b/src/python/grpcio/tests/unit/framework/interfaces/links/test_cases.py
@@ -1,4 +1,4 @@
-# Copyright 2015, Google Inc.
+# Copyright 2015-2016, Google Inc.
 # All rights reserved.
 #
 # Redistribution and use in source and binary forms, with or without
@@ -33,6 +33,8 @@
 import abc
 import unittest  # pylint: disable=unused-import
 
+import six
+
 from grpc.framework.interfaces.links import links
 from tests.unit.framework.common import test_constants
 from tests.unit.framework.interfaces.links import test_utilities
@@ -58,13 +60,12 @@ _TRANSMISSION_GROUP = 'test.Group'
 _TRANSMISSION_METHOD = 'TestMethod'
 
 
-class TransmissionTest(object):
+class TransmissionTest(six.with_metaclass(abc.ABCMeta)):
   """Tests ticket transmission between two connected links.
 
   This class must be mixed into a unittest.TestCase that implements the abstract
   methods it provides.
   """
-  __metaclass__ = abc.ABCMeta
 
   # This is a unittest.TestCase mix-in.
   # pylint: disable=invalid-name