test

packages/svelte/tests/runtime-runes/samples/async-later-sync-overlaps/_config.js

@@ -0,0 +1,30 @@
+import { tick } from 'svelte';
+import { test } from '../../test';
+
+export default test({
+	async test({ assert, target }) {
+		await tick();
+		const [a_b, b, resolve] = target.querySelectorAll('button');
+
+		a_b.click();
+		await tick();
+		assert.htmlEqual(
+			target.innerHTML,
+			'<button>a_b 0_0</button> <button>b 0</button> 0'
+		);
+
+		b.click();
+		await tick();
+		assert.htmlEqual(
+			target.innerHTML,
+			'<button>a_b 0_0</button> <button>b 0</button> 0'
+		);
+
+		resolve.click();
+		await tick();
+		assert.htmlEqual(
+			target.innerHTML,
+			'<button>a_b 1_2</button> <button>b 2</button> 1'
+		);
+	}
+});

packages/svelte/tests/runtime-runes/samples/async-later-sync-overlaps/main.svelte

@@ -0,0 +1,17 @@
+<script>
+	let a = $state(0);
+	let b = $state(0);
+	let deferreds = [];
+
+	function push(value) {
+		if (!value) return value;
+		const deferred = Promise.withResolvers();
+		deferreds.push({ deferred, value });
+		return deferred.promise;
+	}
+</script>
+
+<button onclick={() => {a++;b++}}>a_b {a}_{b}</button>
+<button onclick={() => (b++)}>b {b}</button>
+<button onclick={() => (deferreds.shift()?.())}>resolve</button>
+{await push(a)}