anchor.diff:  
       group('does not warn when multiple children are passed as variadic args', () {
         test('when rendering DOM components', () {
  -        render(
  +        renderWithUniqueOwnerName(() =>
               react.div({},
                 react.span({}),
                 react.span({}),
  
positive.code:       });
  
        test('when rendering custom Dart components', () {
          render(
              CustomComponent({},
                react.span({}),
                react.span({}),
  
negative.code: class _CustomComponent extends react.Component {
    render() => react.div({}, []);
  }
  
  class _OwnerHelperComponent extends react.Component {
    render() => props['render']();
  }
  