'Non-numeric content in a PID file causes a system exit.'

def test_nonNumeric(self):

    pidfile = self.mktemp()
    with open(pidfile, 'w') as f:
        f.write('non-numeric')
    e = self.assertRaises(SystemExit, checkPID, pidfile)
    self.assertIn('non-numeric    value', e.code)
