Test Cases Exercise

MyArrayListWithBugs.java

/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
package myarraylistwithbugs;

/**
 *
 * @author eddmond
 */
public class MyArrayListWithBugs {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        // TODO code application logic here
        MyArrayListWithBugs mylist = new MyArrayListWithBugs();
        mylist.get(0);
    }
    
    private Object[] list;
    int nextFree;

    // Creates a new empty list
    public MyArrayListWithBugs() {
        list = new Object[5];
        nextFree = 0;
    }

    // Inserts object at the end of list
    public void add(Object o) {
        // check capacity
        if (list.length <= nextFree) {
            list = getLongerList();
        }
        list[nextFree] = o;
        nextFree++;
    }

    // Returns the number of objects in the list
    public int size() {
        return nextFree;
    }
    
    // Returns a reference to the object at position index 
    // Throws IndexOutOfBoundsException
    public Object get(int index) {
        if (index < 0 || index >= nextFree) {
            throw new IndexOutOfBoundsException("Error (get): Invalid index"
                    + index);
        }
        
        return list[index];
    }

    // Inserts object at position index
    // Throws IndexOutOfBoundsException
    public void add(int index, Object o) {
        if (index < 0 || nextFree < index) {
            throw new IndexOutOfBoundsException("Error (add): Invalid index"
                    + index);
        }
        // check capacity
        if (list.length <= nextFree) {
            list = getLongerList();
        }
        // Shift elements upwards to make position index free 
        // Start with last element and move backwards
        for (int i = nextFree - 1; i >= index; i--) {
            list[i] = list[i - 1];
        }
        list[index] = o;
        nextFree++;
    }

    // Removes object at position index
    // Returns a reference to the removed object
    // Throws IndexOutOfBoundsException
    public Object remove(int index) {
        if (index < 0 || nextFree <= index) {
            throw new IndexOutOfBoundsException("Error (remove): Invalid index: "
                    + index);
        }
        // Shift elements down to fill indexed position // Start with first element
        for (int i = index; i < nextFree - 1; i++) {
            list[i] = list[i + 1];
        }
        nextFree--;
        return list[index];
    }
//============== private helper methods ========== 
// create a list with double capacity and
// copy all elements to this
    private Object[] getLongerList() {
        Object[] tempList = new Object[list.length * 2];
        System.arraycopy(list, 0, tempList, 0, list.length);
        return tempList;
    }

}

TestCases.java

/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */

import myarraylistwithbugs.MyArrayListWithBugs;
import org.junit.Test;
import static org.junit.Assert.*;
import org.junit.Before;

/**
 *
 * @author eddmond
 */
public class StateDiagramTests {

    String randomObject = "someObject";
    
    @Test
    public void createNewList() {
        MyArrayListWithBugs mylist = new MyArrayListWithBugs();
        int actual = mylist.size();
        int expected = 0;
        assertEquals(expected, actual);
    }

    @Test(expected = IndexOutOfBoundsException.class)
    public void removeFromEmptyList() {
        MyArrayListWithBugs mylist = new MyArrayListWithBugs();
        mylist.remove(0);
    }

    @Test(expected = IndexOutOfBoundsException.class)
    public void getFromEmptyList() {
        MyArrayListWithBugs mylist = new MyArrayListWithBugs();
        mylist.get(0);
    }

    @Test
    public void addNewElement() {
        MyArrayListWithBugs mylist = new MyArrayListWithBugs();
        mylist.add(randomObject);
        int expected = 1;
        int actual = mylist.size();
        assertEquals(expected, actual);
    }

    @Test
    public void getLastAddedElement() {
        MyArrayListWithBugs mylist = new MyArrayListWithBugs();
        mylist.add(randomObject);
        
        Object actual = mylist.get(0);
        assertEquals(randomObject, actual);
    }

    @Test
    public void addSixElements() {
        MyArrayListWithBugs mylist = new MyArrayListWithBugs();
        for (int i = 0; i <= 6; i++) {
            mylist.add(randomObject);
        }
        int expected = 7;
        int actual = mylist.size();
        assertEquals(expected, actual);
    }
    
    @Test
    public void insertAtIndex() {
        MyArrayListWithBugs mylist = new MyArrayListWithBugs();
        mylist.add(0, randomObject);
        
        Object actual = mylist.get(0);
        assertEquals(randomObject, actual);
    }
}