text: test("length is 1", () => {
      expect(WeakSet.prototype.has).toHaveLength(1);
  });
  
  test("basic functionality", () => {
      var original = [{ a: 1 }, { a: 2 }, { a: 3 }];
      var weakSet = new WeakSet(original);
  
      expect(new WeakSet().has()).toBeFalse();
      expect(weakSet.has(original[0])).toBeTrue();
      expect(weakSet.has({ a: 1 })).toBeFalse();
  });
  