修复冻结用户强制下线

backend/internal/modules/chathub/hub_test.go

@@ -0,0 +1,25 @@
+package chathub
+
+import "testing"
+
+func TestDisconnectUserClosesAllConnections(t *testing.T) {
+	hub := NewHub(nil)
+	first := hub.Subscribe("user", 7)
+	second := hub.Subscribe("user", 7)
+	hub.Subscribe("user", 8)
+
+	hub.DisconnectUser(7)
+	for name, ch := range map[string]<-chan *ChatEvent{"first": first, "second": second} {
+		select {
+		case _, ok := <-ch:
+			if ok {
+				t.Fatalf("%s connection was not closed", name)
+			}
+		default:
+			t.Fatalf("%s connection did not close immediately", name)
+		}
+	}
+	if got := hub.OnlineCount(); got != 1 {
+		t.Fatalf("online connection count = %d, want 1", got)
+	}
+}