bridge_with_irc: Check if bot is subscribed to stream at startup.

Author: rht

zulip/integrations/bridge_with_irc/irc_mirror_backend.py

@@ -19,6 +19,8 @@ def __init__(self, zulip_client, stream, topic, channel,
         self.topic = topic
         self.IRC_DOMAIN = server
         self.nickserv_password = nickserv_password
+        # Make sure the bot is subscribed to the stream
+        self.check_subscription_or_die()
 
     def zulip_sender(self, sender_string):
         # type: (str) -> str
@@ -35,6 +37,14 @@ def connect(self, *args, **kwargs):
         )
         print("Connected to IRC server.")
 
+    def check_subscription_or_die(self):
+        # type: () -> None
+        resp = self.zulip_client.list_subscriptions()
+        assert resp["result"] == "success"
+        subs = [s["name"] for s in resp["subscriptions"]]
+        if self.stream not in subs:
+            raise Exception("The bot is not yet subscribed to the specified stream")
+
     def on_nicknameinuse(self, c, e):
         # type: (ServerConnection, Event) -> None
         c.nick(c.get_nickname().replace("_zulip", "__zulip"))