test_cockroach_binary.py

import psycopg2

binary = b'\xff\xd8\xff\xe0\x00\x10'

conn = psycopg2.connect('postgresql://root@localhost:26257/test?sslmode=disable')

with conn as conn, conn.cursor() as c:
    c.execute('select %s::BYTEA', (binary, ))

    rv, = c.fetchone()
    rv = bytes(rv)
    print('got', repr(rv), 'expected', repr(binary))

    assert rv == binary