def test_noKnownHostsOption(self):
        """
        L{default.verifyHostKey} should find your known_hosts file in
        ~/.ssh/known_hosts if you don't specify one explicitly on the command
        line.
        """
        l = []
        tmpdir = self.mktemp()
        oldHostsOption = self.hostsOption
        hostsNonOption = FilePath(tmpdir).child(".ssh").child("known_hosts")
        hostsNonOption.parent().makedirs()
        FilePath(oldHostsOption).moveTo(hostsNonOption)
        self.replaceHome(tmpdir)
        self.options['known-hosts'] = None
        default.verifyHostKey(self.fakeTransport, b"4.3.2.1", sampleKey,
                              b"I don't care.").addCallback(l.append)
        self.assertEqual([1], l)

        L{default.verifyHostKey} should find your known_hosts file in
        ~/.ssh/known_hosts if you don't specify one explicitly on the command
        line.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/conch/test/test_knownhosts.py