on second thoughts

Author: Rich-Harris

packages/svelte/tests/runtime-runes/samples/props-bound-fallback/Counter.svelte

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+<script>
+	let { count = 0 } = $props();
+</script>
+
+<span>{count}</span>

packages/svelte/tests/runtime-runes/samples/props-bound-fallback/_config.js

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+import { test } from '../../test';
+
+// Tests that fallback value is propagated up correctly when the inner component
+// uses a prop it does not write to but has a fallback value
+export default test({
+	accessors: false, // so that prop actually becomes $.prop and not $.prop_source
+	html: `<button>0</button><span>0</span>`,
+
+	async test({ assert, target }) {
+		const btn = target.querySelector('button');
+
+		await btn?.click();
+
+		assert.htmlEqual(target.innerHTML, `<button>1</button><span>1</span>`);
+	},
+
+	error: `Cannot use fallback values with bind:`
+});

packages/svelte/tests/runtime-runes/samples/props-bound-fallback/main.svelte

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+<script>
+    import Counter from './Counter.svelte';
+
+    let bound = $state();
+</script>
+
+<button on:click={() => bound = 1}>{bound}</button>
+
+<Counter bind:count={bound} />