How to test SSH login in localhost

I'm trying to test ssh connectivity similar to the one done by this script but on a local host. The problem with the script below (which I didn't write) is that it requires ssh_pass and does not allow a check on localhost. I've been reading that an expect script might do the trick. I have tried it, but don't have any luck.

Any help would be greatly appreciated!

 #!/bin/bash

STATE_OK=0

STATE_WARNING=1

STATE_CRITICAL=2

STATE_UNKNOWN=3

EXPECTED_RESULT_STRING="This account is currently not available."

while [ $# -gt 0 ]; do
    case $1 in
        -h|--help) help; exit $STATE_OK;;
        -H|--hostname) shift; host=$1; shift;;
        *) usage; exit $STATE_UNKNOWN;;
    esac
done


usage () {
    echo "\
Kerberos 5 KDC plugin for Nagios

-H, --hostname=HOST     Name of KDC to check
-h, --help              Print this help"
}

help () {
    echo; usage;
}



ssh_result=$((/usr/bin/sshpass -f /var/spool/nagios/nagioscheck ssh  -o StrictHostKeyChecking=no  nagioscheck@$host ) 2>&1)

return_code=$?

echo "$ssh_result"
    if [ $grep_status == 0 ]
      then 
        echo "OK ssh login successful and /sbin/nologin exited our session"
        exit $STATE_OK 
    else
      echo "invalid command line arugment or possible issue with /sbin/nologin on host"
      echo "SSH message: $ssh_result"
      exit $STATE_UNKNOWN 
    fi
  ;;
  5)
    echo "CRITICAL SSH password auth failed. Authentication is probably down"
    echo "SSH error message: $ssh_result"
    exit $STATE_CRITICAL
  ;;
  255)
    echo "UNKOWN SSH connection failed for an unknown reason. Return code 255, try checking for a stale known host in /var/spool/nagios/"
    echo "SSH error message: $ssh_result"
    exit $STATE_UNKNOWN
  ;;
  *)
    echo "UNKOWN sshpass failed for an unknown reason. Return code was $return_code"
    echo "SSH error message: $ssh_result"
    exit $STATE_UNKOWN
  ;;
esac