core-js/tests/unit-global/es.async-iterator.async-dispose.js

const { create } = Object;

QUnit.test('AsyncIterator#@@asyncDispose', assert => {
  const asyncDispose = AsyncIterator.prototype[Symbol.asyncDispose];
  assert.isFunction(asyncDispose);
  assert.arity(asyncDispose, 0);
  assert.looksNative(asyncDispose);

  return create(AsyncIterator.prototype)[Symbol.asyncDispose]().then(result => {
    assert.same(result, undefined);
  }).then(() => {
    let called = false;
    const iterator2 = create(AsyncIterator.prototype);
    iterator2.return = function () {
      called = true;
      assert.same(this, iterator2);
      return 7;
    };

    return iterator2[Symbol.asyncDispose]().then(result => {
      assert.same(result, undefined);
      assert.true(called);
    });
  });
});