jQuery Thenable stacking POC

thenable.js

import jQuery from 'jquery';

it('stacks several promises with one rejection', () => {
    const p1 = new jQuery.Deferred();
    const p2 = new jQuery.Deferred();
    const p3 = new jQuery.Deferred();

    const stack = jQuery.when(...promises);

    expect(stack.state()).toBe('pending');
    p3.resolve();
    expect(stack.state()).toBe('pending');
    p2.reject();
    expect(stack.state()).toBe('rejected');
    p1.resolve();
    expect(stack.state()).toBe('rejected');
});

it('stacks several promises with no rejection', () => {
    const p1 = new jQuery.Deferred();
    const p2 = new jQuery.Deferred();
    const p3 = new jQuery.Deferred();

    const stack = jQuery.when(...promises);

    expect(stack.state()).toBe('pending');
    p3.resolve();
    expect(stack.state()).toBe('pending');
    p2.resolve();
    expect(stack.state()).toBe('pending');
    p1.resolve();
    expect(stack.state()).toBe('resolved');
});