'Runs without error and emits settings diff.'

def test_basic(self):

    self.write_settings('settings_to_diff.py', sdict={'FOO': '"bar"'})
    self.addCleanup(self.remove_settings, 'settings_to_diff.py')
    args = ['diffsettings', '--settings=settings_to_diff']
    (out, err) = self.run_manage(args)
    self.assertNoOutput(err)
    self.assertOutput(out, "FOO    =    'bar'        ###")
