core-js/tests/unit-global/es.string.anchor.js

QUnit.test('String#anchor', assert => {
  const { anchor } = String.prototype;
  assert.isFunction(anchor);
  assert.arity(anchor, 1);
  assert.name(anchor, 'anchor');
  assert.looksNative(anchor);
  assert.nonEnumerable(String.prototype, 'anchor');
  assert.same('a'.anchor('b'), '<a name="b">a</a>', 'lower case');
  assert.same('a'.anchor('"'), '<a name="&quot;">a</a>', 'escape quotes');

  if (typeof Symbol == 'function' && !Symbol.sham) {
    const symbol = Symbol('anchor test');
    assert.throws(() => anchor.call(symbol, 'b'), 'throws on symbol context');
    assert.throws(() => anchor.call('a', symbol), 'throws on symbol argument');
  }
});