'Prepares a test client mock to be used.
Args:
client_nr: int The GRR ID to be used. 0xABCD maps to C.100000000000abcd
in canonical representation.
index: client_index.ClientIndex
system: string
os_version: string
arch: string
Returns:
rdf_client.ClientURN'

def SetupClient(self, client_nr, index=None, system=None, os_version=None, arch=None):

    if (index is not None):
        client_id_urn = self._SetupClientImpl(client_nr, index, system, os_version, arch)
    else:
        with client_index.CreateClientIndex(token=self.token) as index:
            client_id_urn = self._SetupClientImpl(client_nr, index, system, os_version, arch)
    return client_id_urn
