unit test for option parser

I want to write a unit test code for OptionParser. Below is my code

 import sys 
 import os
 from optparse import OptionParser
 import socket
 import shutil
 import subprocess
 from subprocess import PIPE
 import glob
 from startup import MYHOME
 sys.path.insert(0, MYHOME)
 HOSTNAME =  socket.gethostname()
 def main():
    usage = "createconfigfiles.py -h for help on usage"
    parser = OptionParser(usage=usage)
    parser.add_option("-a", "--all",
                action="store_true", dest="all", default=False,
                help="copy all config files for %s" % HOSTNAME)    
    parser.add_option("-f", "--first",
                action="store_true", dest="first", default=False,
                help="create and copy all config files when installing 
                     %s" % HOSTNAME)    
    (opts, args) = parser.parse_args()
    def getActualhost():
       hostname = HOSTNAME
       if opts.target:
         target_list = getTargetlist()
         target = opts.target
         if target in target_list:
            hostname = target
         else:
            print '%s is not a known target' % target
            print 'please use any of:', target_list
            return
       return hostname

How can write a unit test for the optionparser. I want to make sure that my main method(which contains command line arguments)working properly. Thanks