let fulfil; let thePromise = new Promise(f => { fulfil = f; }); export default { data: { thePromise }, html: `waiting`, test(assert, component, target) { fulfil(9000); return thePromise .then(() => { assert.htmlEqual(target.innerHTML, `resolved`); let reject; thePromise = new Promise((f, r) => { reject = r; }); component.set({ thePromise }); assert.htmlEqual(target.innerHTML, `waiting`); reject(new Error('something broke')); return thePromise.catch(() => {}); }) .then(() => { assert.htmlEqual(target.innerHTML, `rejected`); }); } };