export default function myInstanceOf(obj, Constructor) {
  throw new Error('Not implemented');
}

import myInstanceOf from './file';

describe('myInstanceOf', () => {
  test('returns true when Constructor.prototype is in the prototype chain', () => {
    function Person() {}
    const p = new Person();
    expect(myInstanceOf(p, Person)).toBe(true);
  });

  test('works for arrays', () => {
    expect(myInstanceOf([], Array)).toBe(true);
    expect(myInstanceOf({}, Array)).toBe(false);
  });

  test('works for functions', () => {
    function f() {}
    expect(myInstanceOf(f, Function)).toBe(true);
  });

  test('returns false for primitives and null/undefined', () => {
    expect(myInstanceOf(1, Number)).toBe(false);
    expect(myInstanceOf('a', String)).toBe(false);
    expect(myInstanceOf(true, Boolean)).toBe(false);
    expect(myInstanceOf(null, Object)).toBe(false);
    expect(myInstanceOf(undefined, Object)).toBe(false);
  });

  test('handles Object.create(null) correctly (null prototype chain)', () => {
    const o = Object.create(null);
    expect(myInstanceOf(o, Object)).toBe(false);
  });

  test('throws if Constructor is not a function', () => {
    try {
      myInstanceOf({}, 123);
      expect(true).toBe(false);
    } catch (e) {
      expect(!!e).toBe(true);
      expect(e.name).toBe('TypeError');
    }
  });
});