update mockrooms so join emits join message

secert-hitler/src/model/state/mockrooms.rs

@@ -1,6 +1,7 @@
 use super::rooms::Rooms;
 use super::room::Room;
 use super::mockroom::MockRoom;
+use super::mockroom::rands;
 
 // #[derive(Clone, Debug)]
 pub struct MockRooms {
@@ -26,7 +27,12 @@ impl Rooms for MockRooms {
    fn join(&self, room_id: String) -> Result<Box<dyn Room>, &str> {
       for r in &self.rooms {
          if r.room_id() == room_id {
-            return Ok(Box::new(r.room()));
+            let mut r = r.room();
+            r.send(format!(r#"{{
+               "displayname": "{}",
+               "membership": "join"
+            }}"#, rands()));
+            return Ok(Box::new(r));
          }
       }
       Err("not found")