add test cases for interceptor (#282)

add test cases for interceptor

Author: arithmetic1728

packages/gapic-generator/tests/system/conftest.py

@@ -12,6 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import collections
 import pytest
 
 from google.showcase import EchoClient
@@ -34,3 +35,54 @@ def identity():
         channel=grpc.insecure_channel('localhost:7469'),
     )
     return IdentityClient(transport=transport)
+
+
+class MetadataClientInterceptor(grpc.UnaryUnaryClientInterceptor,
+                                grpc.UnaryStreamClientInterceptor,
+                                grpc.StreamUnaryClientInterceptor,
+                                grpc.StreamStreamClientInterceptor):
+
+    def __init__(self, key, value):
+        self._key = key
+        self._value = value
+
+    def _add_metadata(self, client_call_details):
+        if client_call_details.metadata is not None:
+            client_call_details.metadata.append((self._key, self._value,))
+
+    def intercept_unary_unary(self, continuation, client_call_details, request):
+        self._add_metadata(client_call_details)
+        response = continuation(client_call_details, request)
+        return response
+
+    def intercept_unary_stream(self, continuation, client_call_details,
+                               request):
+        self._add_metadata(client_call_details)
+        response_it = continuation(client_call_details, request)
+        return response_it
+
+    def intercept_stream_unary(self, continuation, client_call_details,
+                               request_iterator):
+        self._add_metadata(client_call_details)
+        response = continuation(client_call_details, request_iterator)
+        return response
+
+    def intercept_stream_stream(self, continuation, client_call_details,
+                                request_iterator):
+        self._add_metadata(client_call_details)
+        response_it = continuation(client_call_details, request_iterator)
+        return response_it
+
+
+@pytest.fixture
+def intercepted_echo():
+    # The interceptor adds 'showcase-trailer' client metadata. Showcase server
+    # echos any metadata with key 'showcase-trailer', so the same metadata
+    # should appear as trailing metadata in the response.
+    interceptor = MetadataClientInterceptor('showcase-trailer', 'intercepted')
+    channel = grpc.insecure_channel('localhost:7469')
+    intercept_channel = grpc.intercept_channel(channel, interceptor)
+    transport = EchoClient.get_transport_class('grpc')(
+        channel=intercept_channel,
+    )
+    return EchoClient(transport=transport)

packages/gapic-generator/tests/system/test_grpc_interceptor_streams.py

@@ -0,0 +1,46 @@
+# Copyright 2020 Google LLC
+#
+# 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
+#
+#     https://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.
+
+from google import showcase
+
+
+# intercetped_metadata will be added by the interceptor automatically, and
+# showcase server will echo it (since it has key 'showcase-trailer') as trailing
+# metadata.
+intercepted_metadata = (('showcase-trailer', 'intercepted'),)
+
+
+def test_unary_stream(intercepted_echo):
+    content = 'The hail in Wales falls mainly on the snails.'
+    responses = intercepted_echo.expand({
+        'content': content,
+    })
+
+    for ground_truth, response in zip(content.split(' '), responses):
+        assert response.content == ground_truth
+    assert ground_truth == 'snails.'
+
+    assert responses.trailing_metadata() == intercepted_metadata
+
+
+def test_stream_stream(intercepted_echo):
+    requests = []
+    requests.append(showcase.EchoRequest(content="hello"))
+    requests.append(showcase.EchoRequest(content="world!"))
+    responses = intercepted_echo.chat(iter(requests))
+
+    contents = [response.content for response in responses]
+    assert contents == ['hello', 'world!']
+
+    assert responses.trailing_metadata() == intercepted_metadata