From 83d4950a4e266cf07476ead5092b3d6d131988a7 Mon Sep 17 00:00:00 2001
From: Leon Zhao <leeeon233@gmail.com>
Date: Thu, 14 Mar 2024 20:46:18 +0800
Subject: [PATCH] fix: empty diff emits event (#292)

---
 crates/loro-internal/src/state.rs  |  2 +-
 crates/loro-internal/tests/test.rs | 14 ++++++++++++++
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/crates/loro-internal/src/state.rs b/crates/loro-internal/src/state.rs
index 714f077e..98ebb56d 100644
--- a/crates/loro-internal/src/state.rs
+++ b/crates/loro-internal/src/state.rs
@@ -292,7 +292,7 @@ impl DocState {
     /// Panic when the diff cannot be merged with the previous diff.
     /// Caller should call [pre_txn] before calling this to avoid panic.
     fn record_diff(&mut self, diff: InternalDocDiff) {
-        if !self.event_recorder.recording_diff {
+        if !self.event_recorder.recording_diff || diff.diff.is_empty() {
             return;
         }
 
diff --git a/crates/loro-internal/tests/test.rs b/crates/loro-internal/tests/test.rs
index b5fd05a4..5f1cbf5f 100644
--- a/crates/loro-internal/tests/test.rs
+++ b/crates/loro-internal/tests/test.rs
@@ -878,3 +878,17 @@ fn missing_event_when_checkout() {
     doc.attach();
     assert!(value.lock().unwrap().contains_key("b"));
 }
+
+#[test]
+fn empty_event() {
+    let doc = LoroDoc::new_auto_commit();
+    doc.get_map("map").insert("key", 123).unwrap();
+    doc.commit_then_renew();
+    let fire = Arc::new(AtomicBool::new(false));
+    let fire_clone = Arc::clone(&fire);
+    doc.subscribe_root(Arc::new(move |_e| {
+        fire_clone.store(true, std::sync::atomic::Ordering::Relaxed);
+    }));
+    doc.import(&doc.export_snapshot()).unwrap();
+    assert!(!fire.load(std::sync::atomic::Ordering::Relaxed));
+}