Add test

examples/python/cancellation/client.py

@@ -48,7 +48,8 @@ def run_unary_client(server_target, name, ideal_distance):
         stub = hash_name_pb2_grpc.HashFinderStub(channel)
         future = stub.Find.future(
             hash_name_pb2.HashNameRequest(
-                desired_name=name, ideal_hamming_distance=ideal_distance))
+                desired_name=name, ideal_hamming_distance=ideal_distance),
+            wait_for_ready=True)
 
         def cancel_request(unused_signum, unused_frame):
             future.cancel()
@@ -61,6 +62,10 @@ def run_unary_client(server_target, name, ideal_distance):
                 continue
             except grpc.FutureCancelledError:
                 break
+            except grpc.RpcError as rpc_error:
+                if rpc_error.code() == grpc.StatusCode.CANCELLED:
+                    break
+                raise rpc_error
             print(result)
             break
 
@@ -73,7 +78,8 @@ def run_streaming_client(server_target, name, ideal_distance,
             hash_name_pb2.HashNameRequest(
                 desired_name=name,
                 ideal_hamming_distance=ideal_distance,
-                interesting_hamming_distance=interesting_distance))
+                interesting_hamming_distance=interesting_distance),
+            wait_for_ready=True)
 
         def cancel_request(unused_signum, unused_frame):
             result_generator.cancel()

examples/python/cancellation/server.py

@@ -218,6 +218,7 @@ class HashFinder(hash_name_pb2_grpc.HashFinderServicer):
             stop_event.set()
 
         context.add_callback(on_rpc_done)
+        candidates = []
         try:
             candidates = list(
                 _find_secret(request.desired_name,

examples/python/cancellation/test/_cancellation_example_test.py

@@ -0,0 +1,87 @@
+# Copyright 2019 the gRPC authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+"""Test for cancellation example."""
+
+import contextlib
+import os
+import signal
+import socket
+import subprocess
+import unittest
+
+_BINARY_DIR = os.path.realpath(
+    os.path.join(os.path.dirname(os.path.abspath(__file__)), '..'))
+_SERVER_PATH = os.path.join(_BINARY_DIR, 'server')
+_CLIENT_PATH = os.path.join(_BINARY_DIR, 'client')
+
+
+@contextlib.contextmanager
+def _get_port():
+    sock = socket.socket(socket.AF_INET6, socket.SOCK_STREAM)
+    sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEPORT, 1)
+    if sock.getsockopt(socket.SOL_SOCKET, socket.SO_REUSEPORT) == 0:
+        raise RuntimeError("Failed to set SO_REUSEPORT.")
+    sock.bind(('', 0))
+    try:
+        yield sock.getsockname()[1]
+    finally:
+        sock.close()
+
+
+def _start_client(server_port,
+                  desired_string,
+                  ideal_distance,
+                  interesting_distance=None):
+    interesting_distance_args = () if interesting_distance is None else (
+        '--show-inferior', interesting_distance)
+    return subprocess.Popen((_CLIENT_PATH, desired_string, '--server',
+                             'localhost:{}'.format(server_port),
+                             '--ideal-distance',
+                             str(ideal_distance)) + interesting_distance_args)
+
+
+class CancellationExampleTest(unittest.TestCase):
+
+    def test_successful_run(self):
+        with _get_port() as test_port:
+            server_process = subprocess.Popen((_SERVER_PATH, '--port',
+                                               str(test_port)))
+            try:
+                client_process = _start_client(test_port, 'aa', 0)
+                client_return_code = client_process.wait()
+                self.assertEqual(0, client_return_code)
+                self.assertIsNone(server_process.poll())
+            finally:
+                server_process.kill()
+                server_process.wait()
+
+    def test_graceful_sigint(self):
+        with _get_port() as test_port:
+            server_process = subprocess.Popen((_SERVER_PATH, '--port',
+                                               str(test_port)))
+            try:
+                client_process1 = _start_client(test_port, 'aaaaaaaaaa', 0)
+                client_process1.send_signal(signal.SIGINT)
+                client_process1.wait()
+                client_process2 = _start_client(test_port, 'aaaaaaaaaa', 0)
+                client_return_code = client_process2.wait()
+                self.assertEqual(0, client_return_code)
+                self.assertIsNone(server_process.poll())
+            finally:
+                server_process.kill()
+                server_process.wait()
+
+
+if __name__ == '__main__':
+    unittest.main(verbosity=2)