FIX Record instances deserialize properly when returned by agent.ask (#…

…152)

* FIX Record instances deserialize properly when returned by agent.ask

Faust uses an internal model store to keep track of classes deriving from ```Record```.
When sent via Kafka those classes are transparently reconstructed from the deserialized data.
The corresponding logic resides in ```faust.models.base.maybe_model``` which must be used to wrap
the reply value of ```faust.agents.replies.ReplyConsumer._drain_replies```.

* fixed linting

Co-authored-by: tariq <tariq@attariq.de>

faust/agents/replies.py

@@ -12,6 +12,8 @@
 
 __all__ = ["ReplyPromise", "BarrierState", "ReplyConsumer"]
 
+from ..models import maybe_model
+
 
 class ReplyTuple(NamedTuple):
     correlation_id: str
@@ -181,7 +183,7 @@ async def _start_fetcher(self, topic_name: str) -> None:
     async def _drain_replies(self, channel: ChannelT) -> None:
         async for reply in channel.stream():
             for promise in self._waiting[reply.correlation_id]:
-                promise.fulfill(reply.correlation_id, reply.value)
+                promise.fulfill(reply.correlation_id, maybe_model(reply.value))
 
     def _reply_topic(self, topic: str) -> TopicT:
         return self.app.topic(

tests/unit/agents/test_replies.py

@@ -1,12 +1,20 @@
 import asyncio
+import json
 
 import pytest
 from mode.utils.mocks import AsyncMock, Mock
 
+from faust import Record
 from faust.agents.models import ReqRepResponse
 from faust.agents.replies import BarrierState, ReplyConsumer, ReplyPromise
 
 
+class Account(Record, serializer="json"):
+    id: str
+    name: str
+    active: bool = True
+
+
 def test_ReplyPromise():
     r = ReplyPromise(reply_to="rt", correlation_id="id1")
     assert r.reply_to == "rt"
@@ -207,24 +215,35 @@ async def test_start_fetcher(self, *, c):
 
     @pytest.mark.asyncio
     async def test_drain_replies(self, *, c):
+        an_account = Account(id="1", name="aName", active=False)
         responses = [
             ReqRepResponse(key="key1", value="value1", correlation_id="id1"),
             ReqRepResponse(key="key2", value="value2", correlation_id="id2"),
+            ReqRepResponse.from_data(
+                json.loads(
+                    ReqRepResponse(
+                        key="key3", value=an_account, correlation_id="id3"
+                    ).dumps()
+                )
+            ),
         ]
         channel = Mock(
             stream=Mock(return_value=self._response_stream(responses)),
         )
         p1 = Mock()
         p2 = Mock()
         p3 = Mock()
+        p4 = Mock()
         c._waiting["id1"] = {p1, p2}
         c._waiting["id2"] = {p3}
+        c._waiting["id3"] = {p4}
 
         await c._drain_replies(channel)
 
         p1.fulfill.assert_called_once_with("id1", "value1")
         p2.fulfill.assert_called_once_with("id1", "value1")
         p3.fulfill.assert_called_once_with("id2", "value2")
+        p4.fulfill.assert_called_once_with("id3", an_account)
 
     async def _response_stream(self, responses):
         for response in responses: