Bandaid over differences in the C API for Python credentials

src/python/grpcio/grpc/_adapter/_intermediary_low.py

@@ -253,10 +253,10 @@ class Server(object):
 
 
 class ClientCredentials(object):
-  """Adapter from old _low.ClientCredentials interface to new _low.ClientCredentials."""
+  """Adapter from old _low.ClientCredentials interface to new _low.ChannelCredentials."""
 
   def __init__(self, root_certificates, private_key, certificate_chain):
-    self._internal = _low.ClientCredentials.ssl(root_certificates, private_key, certificate_chain)
+    self._internal = _low.ChannelCredentials.ssl(root_certificates, private_key, certificate_chain)
 
 
 class ServerCredentials(object):

src/python/grpcio/grpc/_adapter/_low.py

@@ -33,7 +33,8 @@ from grpc._adapter import _types
 
 _USER_AGENT = 'Python-gRPC-{}'.format(_grpcio_metadata.__version__)
 
-ClientCredentials = _c.ClientCredentials
+ChannelCredentials = _c.ChannelCredentials
+CallCredentials = _c.CallCredentials
 ServerCredentials = _c.ServerCredentials
 
 

src/python/grpcio/grpc/_adapter/_types.py

@@ -323,6 +323,14 @@ class Call:
     """
     return None
 
+  def set_credentials(self, creds):
+    """Set per-call credentials.
+
+    Args:
+      creds (CallCredentials): Credentials to be set for this call.
+    """
+    return None
+
 
 class Channel:
   __metaclass__ = abc.ABCMeta
@@ -334,7 +342,7 @@ class Channel:
     Args:
       target (str): ...
       args (sequence of 2-sequence of str, (str|integer)): ...
-      credentials (ClientCredentials): If None, create an insecure channel,
+      credentials (ChannelCredentials): If None, create an insecure channel,
         else create a secure channel using the client credentials.
     """
 

src/python/grpcio/grpc/beta/interfaces.py

@@ -100,8 +100,11 @@ def grpc_call_options(disable_compression=False, credentials=None):
     disable_compression: A boolean indicating whether or not compression should
       be disabled for the request object of the RPC. Only valid for
       request-unary RPCs.
-    credentials: A ClientCredentials object to use for the invoked RPC.
+    credentials: Reserved for gRPC per-call credentials. The type for this does
+      not exist yet at the Python level.
   """
+  if credentials is not None:
+    raise ValueError('`credentials` is a reserved argument')
   return GRPCCallOptions(disable_compression, None, credentials)
 
 

src/python/grpcio_test/grpc_test/beta/_beta_features_test.py

@@ -181,24 +181,21 @@ class BetaFeaturesTest(unittest.TestCase):
     self._server.stop(test_constants.SHORT_TIMEOUT).wait()
 
   def test_unary_unary(self):
-    call_options = interfaces.grpc_call_options(
-        disable_compression=True, credentials=self._client_credentials)
+    call_options = interfaces.grpc_call_options(disable_compression=True)
     response = getattr(self._dynamic_stub, _UNARY_UNARY)(
         _REQUEST, test_constants.LONG_TIMEOUT, protocol_options=call_options)
     self.assertEqual(_RESPONSE, response)
     self.assertIsNotNone(self._servicer.peer())
 
   def test_unary_stream(self):
-    call_options = interfaces.grpc_call_options(
-        disable_compression=True, credentials=self._client_credentials)
+    call_options = interfaces.grpc_call_options(disable_compression=True)
     response_iterator = getattr(self._dynamic_stub, _UNARY_STREAM)(
         _REQUEST, test_constants.LONG_TIMEOUT, protocol_options=call_options)
     self._servicer.block_until_serviced()
     self.assertIsNotNone(self._servicer.peer())
 
   def test_stream_unary(self):
-    call_options = interfaces.grpc_call_options(
-        credentials=self._client_credentials)
+    call_options = interfaces.grpc_call_options()
     request_iterator = _BlockingIterator(iter((_REQUEST,)))
     response_future = getattr(self._dynamic_stub, _STREAM_UNARY).future(
         request_iterator, test_constants.LONG_TIMEOUT,
@@ -212,8 +209,7 @@ class BetaFeaturesTest(unittest.TestCase):
     self.assertEqual(_RESPONSE, response_future.result())
 
   def test_stream_stream(self):
-    call_options = interfaces.grpc_call_options(
-        credentials=self._client_credentials)
+    call_options = interfaces.grpc_call_options()
     request_iterator = _BlockingIterator(iter((_REQUEST,)))
     response_iterator = getattr(self._dynamic_stub, _STREAM_STREAM)(
         request_iterator, test_constants.SHORT_TIMEOUT,