fix: kick() ignores routing label when _task_queues is narrowed to 1

When with_queues() is used to narrow a broker to a single queue (e.g.
in a worker factory function), kick() hits the `len == 1` shortcut and
hardcodes the routing key to that queue's name, silently ignoring any
explicit queue_name label on the message.

This breaks the common pattern of using a multi-queue broker with
per-worker factory functions, where tasks dispatched from inside a
running task need to route to a different queue:

    broker = AioPikaBroker(..., task_queues=[queue_a, queue_b, queue_c])

    @broker.task(queue_name="queue_b")
    async def mail_task(): ...

    @broker.task  # routes to queue_a by default
    async def default_task():
        await mail_task.kiq()  # silently routed to queue_a, NOT queue_b

    def get_worker_a():
        return broker.with_queues(queue_a)  # narrows _task_queues to 1

Fix: check the routing label first; only fall back to the single-queue
shortcut (backward-compatible) when no explicit label is present.

Author: NicolasFerec

taskiq_aio_pika/broker.py

@@ -336,7 +336,15 @@ def with_queues(self, *queues: Queue) -> Self:
         """
         Replace existing queues with new ones.
 
-        :param queues: queues to add.
+        Commonly used in worker entry-point factory functions to narrow which
+        queue(s) a specific worker process listens to, while the full broker
+        (with all queues) is still used for publishing via kick().
+
+        Note: this only affects which queues the worker *listens* to.
+        Routing at kick() time is still determined by the ``queue_name`` label
+        on the message (or the single-queue fallback for unlabelled tasks).
+
+        :param queues: queues to listen to.
         :return: self.
         """
         self._task_queues = list(queues)
@@ -372,25 +380,32 @@ async def kick(self, message: BrokerMessage) -> None:
         )
         delay = parse_val(float, message.labels.get("delay"))
 
-        if len(self._task_queues) == 1:
-            routing_key_name = (
-                self._task_queues[0].routing_key or self._task_queues[0].name
-            )
-        else:
-            routing_key_name = (
-                parse_val(
-                    str,
-                    message.labels.get(self._label_for_routing),
-                )
-                or ""
-            )
+        # An explicit routing label always takes precedence, regardless of how
+        # many queues are in _task_queues.  This is important when with_queues()
+        # has been used to narrow the listening scope to a single queue: without
+        # this check the len==1 shortcut below would silently override the label
+        # and route every outgoing message to the worker's own queue.
+        routing_key_from_label = parse_val(
+            str,
+            message.labels.get(self._label_for_routing),
+        )
+        if routing_key_from_label:
+            routing_key_name = routing_key_from_label
             if self._exchange.type == ExchangeType.DIRECT and routing_key_name not in {
                 queue.routing_key or queue.name for queue in self._task_queues
             }:
                 raise IncorrectRoutingKeyError(
                     f"Routing key '{routing_key_name}' is not valid. "
                     f"Check routing keys and queue names in broker queues.",
                 )
+        elif len(self._task_queues) == 1:
+            # Backward-compatible shortcut: single-queue brokers don't need to
+            # annotate every task with an explicit queue_name label.
+            routing_key_name = (
+                self._task_queues[0].routing_key or self._task_queues[0].name
+            )
+        else:
+            routing_key_name = ""
 
         if delay is None:
             exchange = await self.write_channel.get_exchange(