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

export default {
	get props() {
		return {
			things: [{ name: 'a' }, { name: 'b' }, { name: 'c' }]
		};
	},

	intro: true,

	test({ assert, component, target, raf }) {
		let divs = target.querySelectorAll('div');
		assert.equal(divs[0].foo, 0);
		assert.equal(divs[1].foo, 0);
		assert.equal(divs[2].foo, 0);

		raf.tick(50);
		assert.equal(divs[0].foo, 0.5);
		assert.equal(divs[1].foo, 0.5);
		assert.equal(divs[2].foo, 0.5);

		component.things = [{ name: 'a' }, { name: 'woo!' }, { name: 'b' }, { name: 'c' }];
		assert.htmlEqual(
			target.innerHTML,
			`
			<div>a</div>
			<div>woo!</div>
			<div>b</div>
			<div>c</div>
		`
		);
		divs = target.querySelectorAll('div');
		assert.equal(divs[0].foo, 0.5);
		assert.equal(divs[1].foo, 0);
		assert.equal(divs[2].foo, 0.5);
		assert.equal(divs[3].foo, 0.5);

		raf.tick(75);
		assert.equal(divs[0].foo, 0.75);
		assert.equal(divs[1].foo, 0.25);
		assert.equal(divs[2].foo, 0.75);
		assert.equal(divs[3].foo, 0.75);
	}
};