bring test over

Author: Rich-Harris

packages/svelte/src/internal/client/reactivity/effects.js

@@ -392,6 +392,7 @@ export function destroy_effect_children(signal, remove_dom = false) {
 		var next = effect.next;
 
 		if ((effect.f & ROOT_EFFECT) !== 0) {
+			// this is now an independent root
 			effect.parent = null;
 		} else {
 			destroy_effect(effect, remove_dom);

packages/svelte/tests/runtime-runes/samples/toStore-teardown/_config.js

@@ -0,0 +1,13 @@
+import { flushSync } from 'svelte';
+import { test } from '../../test';
+
+export default test({
+	async test({ assert, target }) {
+		let [, btn2] = target.querySelectorAll('button');
+
+		btn2.click();
+		flushSync();
+
+		assert.htmlEqual(target.innerHTML, `<button>Set data</button><button>Clear data</button>`);
+	}
+});

packages/svelte/tests/runtime-runes/samples/toStore-teardown/child.svelte

@@ -0,0 +1,11 @@
+<script>
+	import { toStore } from 'svelte/store'
+
+	let { data } = $props()
+	const currentValue = toStore(() => data.value)
+</script>
+
+<p>
+	Current value:
+	<span>{$currentValue}</span>
+</p>

packages/svelte/tests/runtime-runes/samples/toStore-teardown/main.svelte

@@ -0,0 +1,15 @@
+<script>
+	import Child from './child.svelte'
+
+	let data = $state({ value: 'hello' });
+
+	const setData = () => (data = { value: 'hello' })
+	const clearData = () => (data = undefined)
+</script>
+
+<button onclick={setData}>Set data</button>
+<button onclick={clearData}>Clear data</button>
+
+{#if data}
+  <Child {data} />
+{/if}