'If the running ssh-agent does not have a key associated to the given
public key, then ``ssh_agent_has_ssh_key`` returns a deferred that
fails with ``KeyNotFound``.'

def test_public_key_not_in_agent(self):

    key_file = FilePath(self.mktemp())
    generate_ssh_key(key_file)
    create_ssh_agent(key_file, self)
    other_key = generate_ssh_key(FilePath(self.mktemp())).public()
    result = ensure_agent_has_ssh_key(self.reactor, other_key)
    return self.assertFailure(result, KeyNotFound)
