add test for grpcio issue

recipe/meta.yaml

@@ -155,10 +155,13 @@ outputs:
         - {{ pin_subpackage('libgrpc', exact=True) }}
         - __osx >={{ MACOSX_DEPLOYMENT_TARGET|default("10.9") }}  # [osx and x86_64]
     test:
+      source_files:
+        - examples/
       files:
         - grpcio_distribtest.py
       requires:
         - pip
+        - grpcio-tools
       imports:
         - grpc
         - grpc._cython
@@ -173,6 +176,10 @@ outputs:
       commands:
         - python -m pip check
         - python grpcio_distribtest.py
+        # generate helloworld, see https://grpc.io/docs/languages/python/quickstart/#generate-grpc-code
+        - cd examples/python/helloworld
+        - python -m grpc_tools.protoc -I../../protos --python_out=. --pyi_out=. --grpc_python_out=. ../../protos/helloworld.proto
+        - python test_grpcio_helloworld.py
 
 about:
   home: https://grpc.io/

recipe/test_grpcio_helloworld.py

@@ -0,0 +1,12 @@
+# this test assumes it is being run in examples/python/helloworld,
+# after having generated the helloworld_pb2{,_grpc} modules (see meta.yaml)
+import grpc
+import helloworld_pb2
+import helloworld_pb2_grpc
+
+# run this a couple times because it happens randomly, see
+# https://github.com/conda-forge/grpc-cpp-feedstock/issues/281
+for _ in range(1000):
+    with grpc.insecure_channel('localhost:50051') as channel:
+        stub = helloworld_pb2_grpc.GreeterStub(channel)
+        response = stub.SayHello(helloworld_pb2.HelloRequest(name='you'))