def testIgnoredError(self):
        """
        Test that a minus sign '-' at the front of a line ignores
        any errors.
        """
        cmds = """-chown 0 missingFile
pwd
exit
"""
        def _cbCheckResult(res):
            self.assertIn(self.testDir.asBytesMode().path, res)

        d = self._getBatchOutput(cmds)
        d.addCallback(_cbCheckResult)
        return d

        Test that a minus sign '-' at the front of a line ignores
        any errors.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/conch/test/test_cftp.py