'Like test_ciphers, but for the various compressions.'

def test_compressions(self):

    deferreds = []
    for compression in transport.SSHTransportBase.supportedCompressions:
        def setCompression(proto):
            proto.supportedCompressions = [compression]
            return proto
        deferreds.append(self._runClientServer(setCompression))
    return defer.DeferredList(deferreds, fireOnOneErrback=True)
