Correct Python cancel_after_begin interop test

It was a mistake that requests might be sent; the test specification
calls for no requests to be sent. It was a mistake that the response
future's cancelled() method was called; the cancelled() method returns
something more like "was this object's cancel() method called earlier?"
than "did the RPC terminate with status code CANCELLED?". Since it's
something that we'd well enough like to work I've retained the
cancelled() call with a different failure message.

1 files changed, 10 insertions, 10 deletions

diff --git a/src/python/grpcio_tests/tests/interop/methods.py b/src/python/grpcio_tests/tests/interop/methods.py
index 7edd75c56c..c4a0c08430 100644
--- a/src/python/grpcio_tests/tests/interop/methods.py
+++ b/src/python/grpcio_tests/tests/interop/methods.py
@@ -159,16 +159,6 @@ def _server_streaming(stub):
       raise ValueError(
           'response body of invalid size %d!' % len(response.payload.body))
 
-def _cancel_after_begin(stub):
-  sizes = (27182, 8, 1828, 45904,)
-  payloads = (messages_pb2.Payload(body=b'\x00' * size) for size in sizes)
-  requests = (messages_pb2.StreamingInputCallRequest(payload=payload)
-              for payload in payloads)
-  response_future = stub.StreamingInputCall.future(requests)
-  response_future.cancel()
-  if not response_future.cancelled():
-    raise ValueError('expected call to be cancelled')
-
 
 class _Pipe(object):
 
@@ -232,6 +222,16 @@ def _ping_pong(stub):
             'response body of invalid size %d!' % len(response.payload.body))
 
 
+def _cancel_after_begin(stub):
+  with _Pipe() as pipe:
+    response_future = stub.StreamingInputCall.future(pipe)
+    response_future.cancel()
+    if not response_future.cancelled():
+      raise ValueError('expected cancelled method to return True')
+    if response_future.code() is not grpc.StatusCode.CANCELLED:
+      raise ValueError('expected status code CANCELLED')
+
+
 def _cancel_after_first_response(stub):
   request_response_sizes = (31415, 9, 2653, 58979,)
   request_payload_sizes = (27182, 8, 1828, 45904,)