'The all option also shows settings with the default value.'

def test_all(self):

    self.write_settings('settings_to_diff.py', sdict={'STATIC_URL': 'None'})
    self.addCleanup(self.remove_settings, 'settings_to_diff.py')
    args = ['diffsettings', '--settings=settings_to_diff', '--all']
    (out, err) = self.run_manage(args)
    self.assertNoOutput(err)
    self.assertOutput(out, '###    STATIC_URL    =    None')
