svelte/test/runtime/samples/class-with-dynamic-attribute/_config.js

export default {
	data: {
		myClass: 'one two'
	},
	html: `<div class="one two three"></div>`,

	test ( assert, component, target, window ) {
		component.set({ myClass: 'one' });

		assert.htmlEqual( target.innerHTML, `
			<div class="one three"></div>
		` );
	}
};