add skipped failing test

packages/svelte/tests/runtime-runes/samples/async-stale-derived-2/_config.js

@@ -0,0 +1,58 @@
+import { tick } from 'svelte';
+import { test } from '../../test';
+
+export default test({
+	skip: true, // TODO this one is tricky
+
+	async test({ assert, target }) {
+		const [increment, a, b] = target.querySelectorAll('button');
+
+		a.click();
+		await tick();
+
+		assert.htmlEqual(
+			target.innerHTML,
+			`
+				<button>increment</button>
+				<button>shift a</button>
+				<button>shift b</button>
+				<p>a: 0</p>
+			`
+		);
+
+		increment.click();
+		await tick();
+
+		increment.click();
+		await tick();
+
+		increment.click();
+		await tick();
+
+		a.click();
+		await tick();
+
+		assert.htmlEqual(
+			target.innerHTML,
+			`
+				<button>increment</button>
+				<button>shift a</button>
+				<button>shift b</button>
+				<p>a: 0</p>
+			`
+		);
+
+		b.click();
+		await tick();
+
+		assert.htmlEqual(
+			target.innerHTML,
+			`
+				<button>increment</button>
+				<button>shift a</button>
+				<button>shift b</button>
+				<p>b: 0</p
+			`
+		);
+	}
+});

packages/svelte/tests/runtime-runes/samples/async-stale-derived-2/main.svelte

@@ -0,0 +1,34 @@
+<script lang="ts">
+	let count = $state(0);
+
+	let a = [];
+	let b = [];
+
+	function push(deferreds, value) {
+		const deferred = Promise.withResolvers();
+		deferreds.push({ deferred, value });
+		return deferred.promise;
+	}
+</script>
+
+<button onclick={() => count += 1}>increment</button>
+<button onclick={() => {
+	const d = a.shift();
+	d?.deferred.resolve(d.value);
+}}>shift a</button>
+<button onclick={() => {
+	const d = b.shift();
+	d?.deferred.resolve(d.value);
+}}>shift b</button>
+
+<svelte:boundary>
+	{#if count % 2 === 0}
+		<p>a: {await push(a, count)}</p>
+	{:else}
+		<p>b: {await push(b, count)}</p>
+	{/if}
+
+	{#snippet pending()}
+		<p>loading...</p>
+	{/snippet}
+</svelte:boundary>