Honor ConsumerConfig.durable_name in pull_subscribe

nats/src/nats/js/client.py

@@ -580,6 +580,12 @@ async def main():
         if stream is None:
             stream = await self._jsm.find_stream_name_by_subject(subject)
 
+        # Honor a durable name supplied through the config when the durable
+        # argument is omitted, so the consumer is created (and looked up) as a
+        # durable rather than a fresh ephemeral each call.
+        if durable is None and config is not None and config.durable_name:
+            durable = config.durable_name
+
         should_create = True
         try:
             if durable:

nats/tests/test_js.py

@@ -275,6 +275,22 @@ async def test_publish_msg_ttl(self):
 
 
 class PullSubscribeTest(SingleJetStreamServerTestCase):
+    @async_test
+    async def test_pull_subscribe_honors_config_durable_name(self):
+        # Regression for #603: a durable_name supplied via ConsumerConfig must
+        # be honored when the durable argument is omitted, instead of silently
+        # creating a fresh ephemeral consumer.
+        nc = await nats.connect()
+        js = nc.jetstream()
+        await js.add_stream(name="pdur", subjects=["pdur"])
+
+        sub = await js.pull_subscribe("pdur", config=nats.js.api.ConsumerConfig(durable_name="mydurable"))
+        info = await sub.consumer_info()
+        assert info.name == "mydurable"
+        assert info.config.durable_name == "mydurable"
+
+        await nc.close()
+
     @async_test
     async def test_auto_create_consumer(self):
         nc = NATS()