import errno
import hotshot
import hotshot.stats
import os
import sys
import test.pystone


if sys.argv[1:]:
    logfile = sys.argv[1]
else:
    import tempfile
    logf = tempfile.NamedTemporaryFile()
    logfile = logf.name

p = hotshot.Profile(logfile)
benchtime, stones = p.runcall(test.pystone.pystones)
p.close()

print "Pystone(%s) time for %d passes = %g" % \
      (test.pystone.__version__, test.pystone.LOOPS, benchtime)
print "This machine benchmarks at %g pystones/second" % stones

stats = hotshot.stats.load(logfile)
stats.strip_dirs()
stats.sort_stats('time', 'calls')
try:
    stats.print_stats(20)
except IOError, e:
    if e.errno != errno.EPIPE:
        raise

import errno
import hotshot
import hotshot.stats
import os
import sys
import test.pystone

def main(logfile):
    p = hotshot.Profile(logfile)
    benchtime, stones = p.runcall(test.pystone.pystones)
    p.close()

    print "Pystone(%s) time for %d passes = %g" % \
          (test.pystone.__version__, test.pystone.LOOPS, benchtime)
    print "This machine benchmarks at %g pystones/second" % stones

    stats = hotshot.stats.load(logfile)
    stats.strip_dirs()
    stats.sort_stats('time', 'calls')
    try:
        stats.print_stats(20)
    except IOError, e:
        if e.errno != errno.EPIPE:
            raise

if __name__ == '__main__':
    if sys.argv[1:]:
        main(sys.argv[1])
    else:
        import tempfile
        main(tempfile.NamedTemporaryFile().name)

Move testing code into "if __name__ == '__main__'" so it's not run on import.