accounts-frontend/packages/app/polyfills.test.js

import expect from 'app/test/unexpected';

describe('promise.prototype.finally', () => {
  it('should be invoked after promise resolved', () =>
    expect(
      new Promise(resolve => Promise.resolve().finally(resolve)),
      'to be fulfilled',
    ));

  it('should be invoked after promise rejected', () =>
    expect(
      new Promise(resolve =>
        expect(Promise.reject().finally(resolve), 'to be rejected'),
      ),
      'to be fulfilled',
    ));
});