svelte/test/runtime/samples/each-block-keyed/_config.js

export default {
	props: {
		todos: [
			{ id: 123, description: 'implement keyed each blocks' },
			{ id: 234, description: 'implement client-side hydration' }
		]
	},

	html: `
		<p>1: implement keyed each blocks</p>
		<p>2: implement client-side hydration</p>
	`,

	test({ assert, component, target }) {
		const [ p1, p2 ] = target.querySelectorAll('p');

		component.todos = [
			{ id: 234, description: 'implement client-side hydration' }
		];
		assert.htmlEqual(target.innerHTML, '<p>1: implement client-side hydration</p>');

		const [ p3 ] = target.querySelectorAll('p');

		assert.ok(!target.contains(p1), 'first <p> element should be removed');
		assert.equal(p2, p3, 'second <p> element should be retained');
	}
};