self.assertEqual(_hide_login_info(['-u', 'foo', '-p', 'bar']),
['-u', 'PRIVATE', '-p', 'PRIVATE'])
self.assertEqual(_hide_login_info(['-u']), ['-u'])
self.assertEqual(_hide_login_info(['-u', 'foo', '-p', 'bar']),
['-u', 'PRIVATE', '-p', 'PRIVATE'])
self.assertEqual(_hide_login_info(['-u']), ['-u'])