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

export default {
	props: {
		things: [
			{ name: 'a' },
			{ name: 'b' },
			{ name: 'c' }
		]
	},

	intro: true,

	test({ assert, component, target, window, 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);
	}
};