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