esnext.iterator.from.js

import { createIterable, createIterator } from '../helpers/helpers';

const { assign } = Object;

QUnit.test('Iterator.from', assert => {
  const { from } = Iterator;

  assert.isFunction(from);
  assert.arity(from, 1);
  assert.name(from, 'from');
  assert.looksNative(from);
  assert.nonEnumerable(Iterator, 'from');

  assert.true(Iterator.from(createIterator([1, 2, 3])) instanceof Iterator, 'proxy, iterator');

  assert.true(Iterator.from(createIterable([1, 2, 3])) instanceof Iterator, 'proxy, iterable');

  assert.arrayEqual(Iterator.from(createIterable([1, 2, 3])).toArray(), [1, 2, 3], 'just a proxy');

  assert.throws(() => from(undefined), TypeError);
  assert.throws(() => from(null), TypeError);
  assert.throws(() => from({}), TypeError);
  assert.throws(() => from(assign(new Iterator(), { next: 42 })), TypeError);
});