core-js/tests/unit-pure/es.string.iterator.js

import getIterator from 'core-js-pure/es/get-iterator';
// import getIteratorMethod from 'core-js-pure/es/get-iterator-method';
import Symbol from 'core-js-pure/es/symbol';
import from from 'core-js-pure/es/array/from';

QUnit.test('String#@@iterator', assert => {
  let iterator = getIterator('qwe');
  assert.isIterator(iterator);
  assert.same(iterator[Symbol.toStringTag], 'String Iterator');
  assert.same(String(iterator), '[object String Iterator]');
  assert.deepEqual(iterator.next(), {
    value: 'q',
    done: false,
  });
  assert.deepEqual(iterator.next(), {
    value: 'w',
    done: false,
  });
  assert.deepEqual(iterator.next(), {
    value: 'e',
    done: false,
  });
  assert.deepEqual(iterator.next(), {
    value: undefined,
    done: true,
  });
  assert.same(from('𠮷𠮷𠮷').length, 3);
  iterator = getIterator('𠮷𠮷𠮷');
  assert.deepEqual(iterator.next(), {
    value: '𠮷',
    done: false,
  });
  assert.deepEqual(iterator.next(), {
    value: '𠮷',
    done: false,
  });
  assert.deepEqual(iterator.next(), {
    value: '𠮷',
    done: false,
  });
  assert.deepEqual(iterator.next(), {
    value: undefined,
    done: true,
  });

  // early FF case with native method, but polyfilled `Symbol`
  // assert.throws(() => getIteratorMethod('').call(Symbol()), 'throws on symbol context');
});