test: guard effect regression samples

Author: hmnd

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

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+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.notInclude(target.textContent?.trim(), 'hit: true');
+	}
+});

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

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+<script lang="ts">
+	import {untrack} from 'svelte';
+
+	let b = $state(false);
+	let v = $state("one");
+	let hit = $state(false);
+
+	function hitElse(){
+		$effect.root(()=>{
+			if (!untrack(()=>hit)){
+				hit = true
+			}
+		})
+	}
+
+	$effect(() => {
+		v = b ? "one" : "two";
+	})
+</script>
+
+
+<button onclick={() => b = !b}>Trigger</button>
+
+hit: {hit}
+
+{#if v === "one"}
+	<div>if1 matched!</div>
+{:else if v === "two"}
+	<div>if2 matched!</div>
+{:else}
+	<div>nothing matched {hitElse()}</div>
+{/if}

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

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+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

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+<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>