export default function myNew(Constructor, ...args) {
  throw new Error('Not implemented');
}

import myNew from './file';

describe('myNew', () => {
  test('creates an instance with correct prototype and runs constructor', () => {
    function Person(name) { this.name = name; }
    Person.prototype.say = function() { return `hi ${this.name}`; };

    const p = myNew(Person, 'Ada');
    expect(p.name).toBe('Ada');
    expect(p.say()).toBe('hi Ada');
    expect(p instanceof Person).toBe(true);
  });

  test('returns object returned by constructor (override rule)', () => {
    function Factory(name) {
      this.name = name;
      return { ok: true, name };
    }

    const f = myNew(Factory, 'Ada');
    expect(f).toEqual({ ok: true, name: 'Ada' });
  });

  test('ignores primitive returned by constructor', () => {
    function Weird(name) {
      this.name = name;
      return 123;
    }

    const w = myNew(Weird, 'Ada');
    expect(w.name).toBe('Ada');
    expect(w instanceof Weird).toBe(true);
  });

  test('treats null return as no override', () => {
    function NullReturn(name) {
      this.name = name;
      return null;
    }

    const n = myNew(NullReturn, 'Ada');
    expect(n.name).toBe('Ada');
    expect(n instanceof NullReturn).toBe(true);
  });
});