def cert_and_key_from_file(backend, cert_fixture):
    """
    Given a cert fixture, loads the cert and key from a file and returns a cert
    chain object that can be used by PEP 543 TLSConfiguration objects.
    """
    cert = backend.certificate.from_file(cert_fixture['cert'])
    key = backend.private_key.from_file(cert_fixture['key'])
    return ((cert,), key)