// 25: class - extends
// To do: make all tests pass, leave the assert lines unchanged!

describe('classes can inherit from another', () => {

  describe('the default super class is Object', () => {

    it('class A is an instance of Object', () => {
      let A = class A {};
      assert.equal(new A() instanceof Object, true);
    });

    it('B extends A, B is also instance of Object', () => {
      class A {}
      class B extends A {}

      assert.equal(new B() instanceof A, true);
      assert.equal(new B() instanceof Object, true);
    });

    it('class can extend `null`, not an instance of Object', () => {
      class NullClass extends null {}

      let nullInstance = new NullClass();
      assert.equal(nullInstance instanceof Object, false);
    });

  });

  describe('instance of', () => {
    it('when B inherits from A, `new B()` is also an instance of A', () => {
      let A = class A {};
      class B extends A {}

      assert.equal(new B() instanceof A, true);
    });

    it('extend over multiple levels', () => {
      let A = class A {}
      class B extends A {}
      class C extends B {}

      let instance = new C();
      assert.equal(instance instanceof A, true);
    });
  });
});