From 22e0eb3f23a4aef11916f2b4bcea67cd90aa8e17 Mon Sep 17 00:00:00 2001
From: Thomas Weber <thomas.weber@pascom.net>
Date: Thu, 12 Nov 2020 21:28:06 +0100
Subject: [PATCH] Fixed SubscribeOnce unsubscribe handling

---
 event_bus.go      | 6 ++++--
 event_bus_test.go | 7 ++++++-
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/event_bus.go b/event_bus.go
index dedc7fd..718cd4f 100644
--- a/event_bus.go
+++ b/event_bus.go
@@ -136,9 +136,11 @@ func (bus *EventBus) Publish(topic string, args ...interface{}) {
 		// so make a copy and iterate the copied slice.
 		copyHandlers := make([]*eventHandler, len(handlers))
 		copy(copyHandlers, handlers)
-		for i, handler := range copyHandlers {
+		for _, handler := range copyHandlers {
 			if handler.flagOnce {
-				bus.removeHandler(topic, i)
+				// do not rely on copied index, instead lookup the handler in the
+				// possibly altered original list
+				bus.removeHandler(topic, bus.findHandlerIdx(topic, handler.callBack))
 			}
 			if !handler.async {
 				bus.doPublish(handler, topic, args...)
diff --git a/event_bus_test.go b/event_bus_test.go
index 0cdb579..7c37a3b 100644
--- a/event_bus_test.go
+++ b/event_bus_test.go
@@ -52,9 +52,14 @@ func TestSubscribeOnceAndManySubscribe(t *testing.T) {
 	bus.SubscribeOnce(event, fn)
 	bus.Subscribe(event, fn)
 	bus.Subscribe(event, fn)
+	bus.SubscribeOnce(event, fn)
 	bus.Publish(event)
 
-	if flag != 3 {
+	if flag != 4 {
+		t.Fail()
+	}
+	bus.Publish(event)
+	if flag != 6 {
 		t.Fail()
 	}
 }