es6-shim/test-sham/set-prototype-of.js

ECMAScript 6 (Harmony) compatibility shims for legacy JavaScript engines

describe('Object.setPrototypeOf(o, p)', function () {
  'use strict';

  it('changes prototype to regular objects', function () {
    var obj = { a: 123 };
    expect(obj instanceof Object).to.equal(true);
    // sham requires assignment to work cross browser
    obj = Object.setPrototypeOf(obj, null);
    expect(obj instanceof Object).to.equal(false);
    expect(obj.a).to.equal(123);
  });

  it('changes prototype to null objects', function () {
    var obj = Object.create(null);
    obj.a = 456;
    expect(obj instanceof Object).to.equal(false);
    expect(obj.a).to.equal(456);
    // sham requires assignment to work cross browser
    obj = Object.setPrototypeOf(obj, { b: 789 });
    expect(obj instanceof Object).to.equal(true);
    expect(obj.a).to.equal(456);
    expect(obj.b).to.equal(789);
  });
});