getquoted and unicode

I'm currently using psycopg2.extensions.adapt without a connection
intentionally.

The following results in a: psycopg2.InterfaceError: can't encode
unicode string to latin-1

import psycopg2

psycopg2.extensions.register_type(psycopg2.extensions.UNICODE)
adapted = psycopg2.extensions.adapt(u'test')
adapted.getquoted()

Any tips greatly appreciated!