[Python] Migrate from yapf to black (grpc#33138)

- Switched  from yapf to black
- Reconfigure isort for black
- Resolve black/pylint idiosyncrasies 

Note: I used `--experimental-string-processing` because black was
producing "implicit string concatenation", similar to what described
here: psf/black#1837. While currently this
feature is experimental, it will be enabled by default:
psf/black#2188. After running black with the
new string processing so that the generated code merges these `"hello" "
world"` strings concatenations, then I removed
`--experimental-string-processing` for stability, and regenerated the
code again.

To the reviewer: don't even try to open "Files Changed" tab 😄 It's
better to review commit-by-commit, and ignore `run black and isort`.

.gitignore

@@ -23,7 +23,7 @@ src/python/grpcio_*/=*
 src/python/grpcio_*/build/
 src/python/grpcio_*/LICENSE
 src/python/grpcio_status/grpc_status/google/rpc/status.proto
-yapf_virtual_environment/
+black_virtual_environment/
 isort_virtual_environment/
 
 # Node installation output

black.toml

@@ -0,0 +1,51 @@
+[tool.black]
+line-length = 80
+target-version = [
+  "py37",
+  "py38",
+  "py39",
+  "py310",
+  "py311",
+]
+extend-exclude = '''
+# A regex preceded with ^/ will apply only to files and directories
+# in the root of the project.
+(
+  site-packages
+  | test/cpp/naming/resolver_component_tests_runner.py  # AUTO-GENERATED
+  # AUTO-GENERATED from a template:
+  | grpc_version.py
+  | src/python/grpcio/grpc_core_dependencies.py
+  | src/python/grpcio/grpc/_grpcio_metadata.py
+  # AUTO-GENERATED BY make_grpcio_tools.py
+  | tools/distrib/python/grpcio_tools/protoc_lib_deps.py
+  | .*_pb2.py  # autogenerated Protocol Buffer files
+  | .*_pb2_grpc.py  # autogenerated Protocol Buffer gRPC files
+)
+'''
+
+[tool.isort]
+profile = "black"
+line_length = 80
+src_paths = [
+    "examples/python/data_transmission",
+    "examples/python/async_streaming",
+    "tools/run_tests/xds_k8s_test_driver",
+    "src/python/grpcio_tests",
+    "tools/run_tests",
+]
+known_first_party = [
+    "examples",
+    "src",
+]
+known_third_party = ["grpc"]
+skip_glob = [
+    "third_party/*",
+    "*/env/*",
+    "*pb2*.py",
+    "*pb2*.pyi",
+    "**/site-packages/**/*",
+]
+single_line_exclusions = ["typing"]
+force_single_line = true
+force_sort_within_sections = true

examples/python/async_streaming/client.py

@@ -24,9 +24,12 @@
 
 
 class CallMaker:
-
-    def __init__(self, executor: ThreadPoolExecutor, channel: grpc.Channel,
-                 phone_number: str) -> None:
+    def __init__(
+        self,
+        executor: ThreadPoolExecutor,
+        channel: grpc.Channel,
+        phone_number: str,
+    ) -> None:
         self._executor = executor
         self._channel = channel
         self._stub = phone_pb2_grpc.PhoneStub(self._channel)
@@ -39,8 +42,8 @@ def __init__(self, executor: ThreadPoolExecutor, channel: grpc.Channel,
         self._consumer_future = None
 
     def _response_watcher(
-            self,
-            response_iterator: Iterator[phone_pb2.StreamCallResponse]) -> None:
+        self, response_iterator: Iterator[phone_pb2.StreamCallResponse]
+    ) -> None:
         try:
             for response in response_iterator:
                 # NOTE: All fields in Proto3 are optional. This is the recommended way
@@ -52,7 +55,8 @@ def _response_watcher(
                     self._on_call_state(response.call_state.state)
                 else:
                     raise RuntimeError(
-                        "Received StreamCallResponse without call_info and call_state"
+                        "Received StreamCallResponse without call_info and"
+                        " call_state"
                     )
         except Exception as e:
             self._peer_responded.set()
@@ -63,8 +67,11 @@ def _on_call_info(self, call_info: phone_pb2.CallInfo) -> None:
         self._audio_session_link = call_info.media
 
     def _on_call_state(self, call_state: phone_pb2.CallState.State) -> None:
-        logging.info("Call toward [%s] enters [%s] state", self._phone_number,
-                     phone_pb2.CallState.State.Name(call_state))
+        logging.info(
+            "Call toward [%s] enters [%s] state",
+            self._phone_number,
+            phone_pb2.CallState.State.Name(call_state),
+        )
         self._call_state = call_state
         if call_state == phone_pb2.CallState.State.ACTIVE:
             self._peer_responded.set()
@@ -77,8 +84,9 @@ def call(self) -> None:
         request.phone_number = self._phone_number
         response_iterator = self._stub.StreamCall(iter((request,)))
         # Instead of consuming the response on current thread, spawn a consumption thread.
-        self._consumer_future = self._executor.submit(self._response_watcher,
-                                                      response_iterator)
+        self._consumer_future = self._executor.submit(
+            self._response_watcher, response_iterator
+        )
 
     def wait_peer(self) -> bool:
         logging.info("Waiting for peer to connect [%s]...", self._phone_number)
@@ -95,8 +103,9 @@ def audio_session(self) -> None:
         logging.info("Audio session finished [%s]", self._audio_session_link)
 
 
-def process_call(executor: ThreadPoolExecutor, channel: grpc.Channel,
-                 phone_number: str) -> None:
+def process_call(
+    executor: ThreadPoolExecutor, channel: grpc.Channel, phone_number: str
+) -> None:
     call_maker = CallMaker(executor, channel, phone_number)
     call_maker.call()
     if call_maker.wait_peer():
@@ -109,11 +118,12 @@ def process_call(executor: ThreadPoolExecutor, channel: grpc.Channel,
 def run():
     executor = ThreadPoolExecutor()
     with grpc.insecure_channel("localhost:50051") as channel:
-        future = executor.submit(process_call, executor, channel,
-                                 "555-0100-XXXX")
+        future = executor.submit(
+            process_call, executor, channel, "555-0100-XXXX"
+        )
         future.result()
 
 
-if __name__ == '__main__':
+if __name__ == "__main__":
     logging.basicConfig(level=logging.INFO)
     run()

examples/python/async_streaming/server.py

@@ -26,14 +26,14 @@
 
 
 def create_state_response(
-        call_state: phone_pb2.CallState.State) -> phone_pb2.StreamCallResponse:
+    call_state: phone_pb2.CallState.State,
+) -> phone_pb2.StreamCallResponse:
     response = phone_pb2.StreamCallResponse()
     response.call_state.state = call_state
     return response
 
 
 class Phone(phone_pb2_grpc.PhoneServicer):
-
     def __init__(self):
         self._id_counter = 0
         self._lock = threading.RLock()
@@ -51,13 +51,16 @@ def _clean_call_session(self, call_info: phone_pb2.CallInfo) -> None:
         logging.info("Call session cleaned [%s]", MessageToJson(call_info))
 
     def StreamCall(
-        self, request_iterator: Iterable[phone_pb2.StreamCallRequest],
-        context: grpc.ServicerContext
+        self,
+        request_iterator: Iterable[phone_pb2.StreamCallRequest],
+        context: grpc.ServicerContext,
     ) -> Iterable[phone_pb2.StreamCallResponse]:
         try:
             request = next(request_iterator)
-            logging.info("Received a phone call request for number [%s]",
-                         request.phone_number)
+            logging.info(
+                "Received a phone call request for number [%s]",
+                request.phone_number,
+            )
         except StopIteration:
             raise RuntimeError("Failed to receive call request")
         # Simulate the acceptance of call request

examples/python/auth/_credentials.py

@@ -18,10 +18,10 @@
 
 def _load_credential_from_file(filepath):
     real_path = os.path.join(os.path.dirname(__file__), filepath)
-    with open(real_path, 'rb') as f:
+    with open(real_path, "rb") as f:
         return f.read()
 
 
-SERVER_CERTIFICATE = _load_credential_from_file('credentials/localhost.crt')
-SERVER_CERTIFICATE_KEY = _load_credential_from_file('credentials/localhost.key')
-ROOT_CERTIFICATE = _load_credential_from_file('credentials/root.crt')
+SERVER_CERTIFICATE = _load_credential_from_file("credentials/localhost.crt")
+SERVER_CERTIFICATE_KEY = _load_credential_from_file("credentials/localhost.key")
+ROOT_CERTIFICATE = _load_credential_from_file("credentials/root.crt")

examples/python/auth/async_customized_auth_client.py

@@ -21,19 +21,22 @@
 import grpc
 
 helloworld_pb2, helloworld_pb2_grpc = grpc.protos_and_services(
-    "helloworld.proto")
+    "helloworld.proto"
+)
 
 _LOGGER = logging.getLogger(__name__)
 _LOGGER.setLevel(logging.INFO)
 
-_SERVER_ADDR_TEMPLATE = 'localhost:%d'
-_SIGNATURE_HEADER_KEY = 'x-signature'
+_SERVER_ADDR_TEMPLATE = "localhost:%d"
+_SIGNATURE_HEADER_KEY = "x-signature"
 
 
 class AuthGateway(grpc.AuthMetadataPlugin):
-
-    def __call__(self, context: grpc.AuthMetadataContext,
-                 callback: grpc.AuthMetadataPluginCallback) -> None:
+    def __call__(
+        self,
+        context: grpc.AuthMetadataContext,
+        callback: grpc.AuthMetadataPluginCallback,
+    ) -> None:
         """Implements authentication by passing metadata to a callback.
 
         Implementations of this method must not block.
@@ -54,11 +57,13 @@ def __call__(self, context: grpc.AuthMetadataContext,
 
 def create_client_channel(addr: str) -> grpc.aio.Channel:
     # Call credential object will be invoked for every single RPC
-    call_credentials = grpc.metadata_call_credentials(AuthGateway(),
-                                                      name='auth gateway')
+    call_credentials = grpc.metadata_call_credentials(
+        AuthGateway(), name="auth gateway"
+    )
     # Channel credential will be valid for the entire channel
     channel_credential = grpc.ssl_channel_credentials(
-        _credentials.ROOT_CERTIFICATE)
+        _credentials.ROOT_CERTIFICATE
+    )
     # Combining channel credentials and call credentials together
     composite_credentials = grpc.composite_channel_credentials(
         channel_credential,
@@ -70,31 +75,33 @@ def create_client_channel(addr: str) -> grpc.aio.Channel:
 
 async def send_rpc(channel: grpc.aio.Channel) -> helloworld_pb2.HelloReply:
     stub = helloworld_pb2_grpc.GreeterStub(channel)
-    request = helloworld_pb2.HelloRequest(name='you')
+    request = helloworld_pb2.HelloRequest(name="you")
     try:
         response = await stub.SayHello(request)
     except grpc.RpcError as rpc_error:
-        _LOGGER.error('Received error: %s', rpc_error)
+        _LOGGER.error("Received error: %s", rpc_error)
         return rpc_error
     else:
-        _LOGGER.info('Received message: %s', response)
+        _LOGGER.info("Received message: %s", response)
         return response
 
 
 async def main() -> None:
     parser = argparse.ArgumentParser()
-    parser.add_argument('--port',
-                        nargs='?',
-                        type=int,
-                        default=50051,
-                        help='the address of server')
+    parser.add_argument(
+        "--port",
+        nargs="?",
+        type=int,
+        default=50051,
+        help="the address of server",
+    )
     args = parser.parse_args()
 
     channel = create_client_channel(_SERVER_ADDR_TEMPLATE % args.port)
     await send_rpc(channel)
     await channel.close()
 
 
-if __name__ == '__main__':
+if __name__ == "__main__":
     logging.basicConfig(level=logging.INFO)
     asyncio.run(main())