allow preconfigured redis clients

broadcaster/backends/redis.py

@@ -10,19 +10,26 @@
 
 
 class RedisBackend(BroadcastBackend):
-    def __init__(self, url: str):
-        self._conn = redis.Redis.from_url(url)
+    _conn: redis.Redis
+
+    def __init__(self, url: str | None = None, *, conn: redis.Redis | None = None):
+        if url is None:
+            assert conn is not None, "conn must be provided if url is not"
+            self._conn = conn
+        else:
+            self._conn = redis.Redis.from_url(url)
+
         self._pubsub = self._conn.pubsub()
         self._ready = asyncio.Event()
         self._queue: asyncio.Queue[Event] = asyncio.Queue()
         self._listener: asyncio.Task[None] | None = None
 
     async def connect(self) -> None:
         self._listener = asyncio.create_task(self._pubsub_listener())
-        await self._pubsub.connect()
+        await self._pubsub.connect()  # type: ignore[no-untyped-call]
 
     async def disconnect(self) -> None:
-        await self._pubsub.aclose()
+        await self._pubsub.aclose()  # type: ignore[no-untyped-call]
         await self._conn.aclose()
         if self._listener is not None:
             self._listener.cancel()

tests/test_broadcast.py

@@ -4,9 +4,11 @@
 import typing
 
 import pytest
+from redis import asyncio as redis
 
 from broadcaster import Broadcast, BroadcastBackend, Event
 from broadcaster.backends.kafka import KafkaBackend
+from broadcaster.backends.redis import RedisBackend
 
 
 class CustomBackend(BroadcastBackend):
@@ -56,6 +58,23 @@ async def test_redis():
             assert event.message == "hello"
 
 
+@pytest.mark.asyncio
+async def test_redis_configured_client():
+    backend = RedisBackend(conn=redis.Redis.from_url("redis://localhost:6379"))
+    async with Broadcast(backend=backend) as broadcast:
+        async with broadcast.subscribe("chatroom") as subscriber:
+            await broadcast.publish("chatroom", "hello")
+            event = await subscriber.get()
+            assert event.channel == "chatroom"
+            assert event.message == "hello"
+
+
+@pytest.mark.asyncio
+async def test_redis_requires_url_or_connection():
+    with pytest.raises(AssertionError, match="conn must be provided if url is not"):
+        RedisBackend()
+
+
 @pytest.mark.asyncio
 async def test_redis_stream():
     async with Broadcast("redis-stream://localhost:6379") as broadcast: