test: guard effect regression samples

Author: hmnd

packages/svelte/tests/runtime-runes/samples/guard-else-effect/_config.js

@@ -0,0 +1,22 @@
+import { expect, vi } from 'vitest';
+import { test } from '../../test';
+import { flushSync } from 'svelte';
+
+const trackBranch = vi.fn();
+
+export default test({
+	mode: ['client'],
+	props: { trackBranch: trackBranch },
+	async test({ target }) {
+		const button = target.querySelector('button');
+
+		flushSync(() => button?.click());
+		flushSync(() => button?.click());
+		flushSync(() => button?.click());
+		flushSync(() => button?.click());
+
+		expect(trackBranch).toHaveBeenCalledWith('one');
+		expect(trackBranch).toHaveBeenCalledWith('two');
+		expect(trackBranch).not.toHaveBeenCalledWith('else');
+	}
+});

packages/svelte/tests/runtime-runes/samples/guard-else-effect/main.svelte

@@ -0,0 +1,25 @@
+<script lang="ts">
+	import {untrack} from 'svelte';
+
+	const {trackBranch}:{trackBranch: (branch:string)=>void} = $props();
+
+	let b = $state(false);
+	let v = $state("two");
+
+
+	$effect(() => {
+		v = b ? "one" : "two";
+	})
+</script>
+
+
+<button onclick={() => b = !b}>Trigger</button>
+
+
+{#if v === "one"}
+	<div>if1 matched! {trackBranch('one')}</div>
+{:else if v === "two"}
+	<div>if2 matched! {trackBranch('two')}</div>
+{:else}
+	<div>nothing matched {trackBranch('else')}</div>
+{/if}

packages/svelte/tests/runtime-runes/samples/guard-if-nested/_config.js

@@ -0,0 +1,13 @@
+import { test } from '../../test';
+import { flushSync } from 'svelte';
+
+export default test({
+	mode: ['client'],
+	async test({ target, assert }) {
+		const button = target.querySelector('button');
+
+		flushSync(() => button?.click());
+
+		assert.equal(target.textContent?.trim(), 'Trigger');
+	}
+});

packages/svelte/tests/runtime-runes/samples/guard-if-nested/main.svelte

@@ -0,0 +1,19 @@
+<script>
+	let centerRow = $state({ nested: { optional: 2, required: 3 } },
+		);
+
+	let someChange = $state(false);
+	$effect(() => {
+		if (someChange) centerRow = undefined;
+	});
+</script>
+
+	{#if centerRow?.nested}
+		{#if centerRow?.nested?.optional != undefined && centerRow.nested.optional > 0}
+			op: {centerRow.nested.optional}<br />
+		{:else}
+			req: {centerRow.nested.required}<br />
+		{/if}
+	{/if}
+
+<button onclick={() => (someChange = true)}>Trigger</button>