From 392e83be42da8f371671083ddcd5ca129fd0451d Mon Sep 17 00:00:00 2001
From: Yuya Nishihara <yuya@tcha.org>
Date: Tue, 2 Jan 2024 16:11:31 +0900
Subject: [PATCH] op_heads: ensure that update_op_heads([id], id) fails

The doc states it's invalid, but I made such bug.
---
 lib/src/simple_op_heads_store.rs | 1 +
 1 file changed, 1 insertion(+)

diff --git a/lib/src/simple_op_heads_store.rs b/lib/src/simple_op_heads_store.rs
index 44e3928a3..7603ffed8 100644
--- a/lib/src/simple_op_heads_store.rs
+++ b/lib/src/simple_op_heads_store.rs
@@ -76,6 +76,7 @@ impl OpHeadsStore for SimpleOpHeadsStore {
     }
 
     fn update_op_heads(&self, old_ids: &[OperationId], new_id: &OperationId) {
+        assert!(!old_ids.contains(new_id));
         self.add_op_head(new_id);
         for old_id in old_ids {
             self.remove_op_head(old_id)