From 7c6cceb1c05786754d00bec867f23492ee5a3f19 Mon Sep 17 00:00:00 2001
From: Dominic Gannaway <dg@domgan.com>
Date: Thu, 14 Mar 2024 13:15:42 +0000
Subject: [PATCH] add test case

---
 packages/svelte/src/reactivity/map.test.ts | 26 ++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/packages/svelte/src/reactivity/map.test.ts b/packages/svelte/src/reactivity/map.test.ts
index e50696309b..fbbb11e340 100644
--- a/packages/svelte/src/reactivity/map.test.ts
+++ b/packages/svelte/src/reactivity/map.test.ts
@@ -123,3 +123,29 @@ test('map.has(...)', () => {
 
 	cleanup();
 });
+
+test('map handling of undefined values', () => {
+	const map = new ReactiveMap();
+
+	const log: any = [];
+
+	const cleanup = user_root_effect(() => {
+		map.set(1, undefined);
+
+		pre_effect(() => {
+			log.push(map.get(1));
+		});
+
+		flushSync(() => {
+			map.delete(1);
+		});
+
+		flushSync(() => {
+			map.set(1, 1);
+		});
+	});
+
+	assert.deepEqual(log, [undefined, undefined, 1]);
+
+	cleanup();
+});