WIP

packages/svelte/tests/runtime-runes/samples/async-derived/Child.svelte

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+<script>
+	let { promise, num } = $props();
+
+	let value = $derived((await promise) * num);
+</script>
+
+<p>{value}</p>

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

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+import { tick } from 'svelte';
+import { deferred } from '../../../../src/internal/shared/utils.js';
+import { test } from '../../test';
+
+/** @type {ReturnType<typeof deferred>} */
+let d;
+
+export default test({
+	html: `<p>pending</p>`,
+
+	get props() {
+		d = deferred();
+
+		return {
+			promise: d.promise,
+			num: 1
+		};
+	},
+
+	async test({ assert, target }) {
+		d.resolve('hello');
+		await Promise.resolve();
+		await Promise.resolve();
+		await Promise.resolve();
+		await tick();
+		assert.htmlEqual(target.innerHTML, '<p>42</p>');
+	}
+});

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

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+<script>
+	import Child from './Child.svelte';
+
+	let { promise, num } = $props();
+</script>
+
+<svelte:boundary>
+	<Child {promise} {num} />
+
+	{#snippet pending()}
+		<p>pending</p>
+	{/snippet}
+</svelte:boundary>