log some information for empty invitee list

Author: jcai

wechaty/src/main/scala/wechaty/plugins/RoomJoinHello.scala

@@ -17,7 +17,9 @@ class RoomJoinHello(config:RoomJoinHelloConfig) extends WechatyPlugin with LazyL
       val rooms = PluginHelper.findRooms(config.rooms)
       rooms.foreach(room=>{
         room.onJoin{case (list,_,_)=>
-          room.say(config.hello,list)
+          if(list==null || list.isEmpty ){
+            logger.warn("invitee list is empty")
+          }else room.say(config.hello,list)
         }
       })
       logger.info("install RoomJoinHello Plugin done")

wechaty/src/test/scala/wechaty/plugins/RoomJoinHelloTest.scala

@@ -25,6 +25,14 @@ class RoomJoinHelloTest extends TestBase{
     mockContactPayload("jcai")
     val payload=new EventRoomJoinPayload
     payload.roomId="roomId"
+    payload.inviteeIdList=Array()
+    instance.puppet.emit(PuppetEventName.ROOM_JOIN,payload)
+
+    verifyThat(
+      calledMethod(PuppetGrpc.getMessageSendTextMethod),
+      times(0));
+
+
     payload.inviteeIdList=Array("jcai")
     instance.puppet.emit(PuppetEventName.ROOM_JOIN,payload)