'Test for silent failure when target variable isn\'t found'

@setup({'regroup02': '{%    regroup    data    by    bar    as    grouped    %}{%    for    group    in    grouped    %}{{    group.grouper    }}:{%    for    item    in    group.list    %}{{    item.foo    }}{%    endfor    %}{%    endfor    %}'})
def test_regroup02(self):

    output = self.engine.render_to_string('regroup02', {})
    self.assertEqual(output, '')
