From e1cea16050dbc80d666143c74565c1f301a64854 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Tue, 12 Nov 2024 08:42:13 -0500
Subject: [PATCH] add failing test for #14268

---
 .../_config.js                                   | 16 ++++++++++++++++
 .../main.svelte                                  |  7 +++++++
 2 files changed, 23 insertions(+)
 create mode 100644 packages/svelte/tests/runtime-runes/samples/proxy-nullish-coalescing-assignment/_config.js
 create mode 100644 packages/svelte/tests/runtime-runes/samples/proxy-nullish-coalescing-assignment/main.svelte

diff --git a/packages/svelte/tests/runtime-runes/samples/proxy-nullish-coalescing-assignment/_config.js b/packages/svelte/tests/runtime-runes/samples/proxy-nullish-coalescing-assignment/_config.js
new file mode 100644
index 000000000000..4edeec858d40
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/proxy-nullish-coalescing-assignment/_config.js
@@ -0,0 +1,16 @@
+import { flushSync } from 'svelte';
+import { test } from '../../test';
+
+export default test({
+	html: `<button>items: null</button>`,
+
+	test({ assert, target }) {
+		const btn = target.querySelector('button');
+
+		flushSync(() => btn?.click());
+		assert.htmlEqual(target.innerHTML, `<button>items: [0]</button>`);
+
+		flushSync(() => btn?.click());
+		assert.htmlEqual(target.innerHTML, `<button>items: [0,1]</button>`);
+	}
+});
diff --git a/packages/svelte/tests/runtime-runes/samples/proxy-nullish-coalescing-assignment/main.svelte b/packages/svelte/tests/runtime-runes/samples/proxy-nullish-coalescing-assignment/main.svelte
new file mode 100644
index 000000000000..84c1c32c5cc8
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/proxy-nullish-coalescing-assignment/main.svelte
@@ -0,0 +1,7 @@
+<script>
+	let items = $state(null);
+</script>
+
+<button onclick={() => (items ??= []).push(items.length)}>
+	items: {JSON.stringify(items)}
+</button>