How to auto-test an image using pexpect

virt-pexpect.py

import pexpect

image = "fedora-20.img"
user = "root"
password = "changeme"

# Define the qemu cmd to run
# The important bit is to redirect the serial to stdio
cmd = "qemu-kvm"
cmd += " -m 1024 -serial stdio -net user -net nic"
cmd += " -snapshot -hda %s" % image
cmd += " -watchdog-action poweroff"

# Spawn the qemu process and log to stdout
child = pexpect.spawn(cmd)
child.logfile = sys.stdout

# Now wait for the login
child.expect('(?i)login:')

# And login with the credentials from above
child.sendline(user)
child.expect('(?i)password:')
child.sendline(password)
child.expect('# ')

# Now shutdown the machine and end the process
if child.isalive():
    child.sendline('init 0')
    child.close()

if child.isalive():
    print('Child did not exit gracefully.')
else:
    print('Child exited gracefully.')