test: error when ACK is sent without message

src/Server.hs

@@ -64,9 +64,8 @@ runClient h = do
     `finally` cancelSubscribers c
 
 cancelSubscribers :: (MonadUnliftIO m) => Client -> m ()
-cancelSubscribers Client {subscriptions} = do
-  cs <- readTVarIO subscriptions
-  forM_ cs cancelSub
+cancelSubscribers Client {subscriptions} =
+  readTVarIO subscriptions >>= mapM_ cancelSub
 
 cancelSub :: (MonadUnliftIO m) => Sub -> m ()
 cancelSub = \case
@@ -84,7 +83,7 @@ receive h Client {rcvQ} = forever $ do
   (signature, (connId, cmdOrError)) <- tGet fromClient h
   -- TODO maybe send Either to queue?
   signed <- case cmdOrError of
-    Left e -> return . (connId,) . Cmd SBroker $ ERR e
+    Left e -> return . mkResp connId $ ERR e
     Right cmd -> verifyTransmission signature connId cmd
   atomically $ writeTBQueue rcvQ signed
 
@@ -93,6 +92,9 @@ send h Client {sndQ} = forever $ do
   signed <- atomically $ readTBQueue sndQ
   tPut h (B.empty, signed)
 
+mkResp :: ConnId -> Command 'Broker -> Signed
+mkResp connId command = (connId, Cmd SBroker command)
+
 verifyTransmission :: forall m. (MonadUnliftIO m, MonadReader Env m) => Signature -> ConnId -> Cmd -> m Signed
 verifyTransmission signature connId cmd = do
   (connId,) <$> case cmd of
@@ -253,9 +255,6 @@ client clnt@Client {subscriptions, rcvQ, sndQ} Server {subscribedQ} =
               Left e -> return $ err e
               Right _ -> delMsgQueue ms connId $> ok
 
-        mkResp :: ConnId -> Command 'Broker -> Signed
-        mkResp cId command = (cId, Cmd SBroker command)
-
         ok :: Signed
         ok = mkResp connId OK
 

tests/Test.hs

@@ -56,6 +56,9 @@ testCreateSecure =
       Resp _ ok4 <- sendRecv h ("1234", rId, "ACK")
       (ok4, OK) #== "replies OK when message acknowledged if no more messages"
 
+      Resp _ err6 <- sendRecv h ("1234", rId, "ACK")
+      (err6, ERR PROHIBITED) #== "replies ERR when message acknowledged without messages"
+
       Resp sId2 err1 <- sendRecv h ("4567", sId, "SEND :hello")
       (err1, ERR AUTH) #== "rejects signed SEND"
       (sId2, sId) #== "same connection ID in response 2"