fix: ensure exception is available when BackgroundConsumer open stream fails (#357)

* fix: ensure exception is available when BackgroundConsumer open stream fails

* chore: fix coverage

* Address review comments

* revert

* address review feedback

* raise grpc.RpcError instead of GoogleAPICallError

* 🦉 Updates from OwlBot post-processor

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---------

Co-authored-by: Rosie Zou <rosiezou@users.noreply.github.com>
Co-authored-by: Owl Bot <gcf-owl-bot[bot]@users.noreply.github.com>

Author: 3 people

Diff for: google/api_core/bidi.py

@@ -92,10 +92,7 @@ def _is_active(self):
         # Note: there is a possibility that this starts *before* the call
         # property is set. So we have to check if self.call is set before
         # seeing if it's active.
-        if self.call is not None and not self.call.is_active():
-            return False
-        else:
-            return True
+        return self.call is not None and self.call.is_active()
 
     def __iter__(self):
         if self._initial_request is not None:
@@ -265,6 +262,10 @@ def add_done_callback(self, callback):
         self._callbacks.append(callback)
 
     def _on_call_done(self, future):
+        # This occurs when the RPC errors or is successfully terminated.
+        # Note that grpc's "future" here can also be a grpc.RpcError.
+        # See note in https://github.com/grpc/grpc/issues/10885#issuecomment-302651331
+        # that `grpc.RpcError` is also `grpc.call`.
         for callback in self._callbacks:
             callback(future)
 
@@ -276,7 +277,13 @@ def open(self):
         request_generator = _RequestQueueGenerator(
             self._request_queue, initial_request=self._initial_request
         )
-        call = self._start_rpc(iter(request_generator), metadata=self._rpc_metadata)
+        try:
+            call = self._start_rpc(iter(request_generator), metadata=self._rpc_metadata)
+        except exceptions.GoogleAPICallError as exc:
+            # The original `grpc.RpcError` (which is usually also a `grpc.Call`) is
+            # available from the ``response`` property on the mapped exception.
+            self._on_call_done(exc.response)
+            raise
 
         request_generator.call = call
 

Diff for: tests/unit/test_bidi.py

@@ -804,6 +804,21 @@ def test_wake_on_error(self):
         while consumer.is_active:
             pass
 
+    def test_rpc_callback_fires_when_consumer_start_fails(self):
+        expected_exception = exceptions.InvalidArgument(
+            "test", response=grpc.StatusCode.INVALID_ARGUMENT
+        )
+        callback = mock.Mock(spec=["__call__"])
+
+        rpc, _ = make_rpc()
+        bidi_rpc = bidi.BidiRpc(rpc)
+        bidi_rpc.add_done_callback(callback)
+        bidi_rpc._start_rpc.side_effect = expected_exception
+
+        consumer = bidi.BackgroundConsumer(bidi_rpc, on_response=None)
+        consumer.start()
+        assert callback.call_args.args[0] == grpc.StatusCode.INVALID_ARGUMENT
+
     def test_consumer_expected_error(self, caplog):
         caplog.set_level(logging.DEBUG)