I would like to write a jUnit test case for the code which checks getRooms and getEmployees method, dont know where to begin

/*modified code from University of South Carolina: package MeetingPlanner */ package Planner;

import java.util.ArrayList;

public class Organization { /** This class is used to initialize and store a list of employees * and rooms available for meetings. * * It gets a bunch of initialization code out of the PlannerInterface. */

private ArrayList<Person> employees;
private ArrayList<Room> rooms;

/**
 * Default constructor - sets up some rooms and people.
 */
public Organization(){
    employees = new ArrayList<Person>();
    employees.add(new Person("Justin Gardener"));
    employees.add(new Person("Ashley Matthews"));
    employees.add(new Person("Mary Jane Cook"));
    employees.add(new Person("Rose Austin"));
    employees.add(new Person("Mike Smith"));
    employees.add(new Person("Helen West"));
    employees.add(new Person("Steven Lewis"));
    employees.add(new Person("Edith Cowan"));
    employees.add(new Person("Mark Colin"));
    employees.add(new Person("Jacquie Martin"));

    rooms = new ArrayList<Room>();
    rooms.add(new Room("JO18.330"));
    rooms.add(new Room("JO7.221"));
    rooms.add(new Room("JO15.236"));
    rooms.add(new Room("JO1.230"));
    rooms.add(new Room("ML5.123"));
    rooms.add(new Room("ML18.330"));
    rooms.add(new Room("ML21.520"));
    rooms.add(new Room("ML13.213"));
}

public ArrayList<Person> getEmployees() {
    return employees;
}

public ArrayList<Room> getRooms() {
    return rooms;
}

/**
 * Search for and retrieve a room.
 * @param ID - ID of the room to retrieve.
 * @return Room - The requested Room object.
 * @throws Exception - If the room does not exist.
 */
public Room getRoom(String ID) throws Exception{
    Room room = null;
    for(Room toCheck : rooms){
        if(toCheck.getID().equals(ID)){
            room = toCheck;
            return room;
        }
    }

    throw new Exception("Requested room does not exist");
}

/**
 * Search for and retrieve a person.
 * @param name - The name of the person to retrieve.
 * @return Person - The requested Person object.
 * @throws Exception - If the person does not exist.
 */
public Person getEmployee(String name) throws Exception{
    Person employee = null;
    for(Person toCheck : employees){
        if(toCheck.getName().equals(name)){
            employee = toCheck;
            return employee;
        }
    }

    throw new Exception("Requested employee does not exist");
}

}