Assignment 1 Junit Test Solution

Part I: You are given the following LinkedStack.java file which includes the implementation of Stack using LinkedList data structure.




import java.util.NoSuchElementException;




public class LinkedStack<Item{

    private int n;          // size of the stack

    private Node first;     // top of stack




    private class Node {

        private Item item;

        private Node next;

    }




    //initializes an empty stack.

    public LinkedStack() {

        first = null;

        n = 0;

    }




    //returns true if this stack is empty; false otherwise

    public boolean isEmpty() {

        return first == null;

    }




    //returns the number of items in the stack.

    public int size() {

        return n;

    }




    //inserts an item to the stack 

    public void push(Item item) {

        Node temp = first;

        first = new Node();

        first.item = item;

        first.next = temp;

        n++;

    }

    //removes and returns the top element in the stack

    public Item pop()  {

        if (isEmpty()) throw new ArrayIndexOutOfBoundsException("Stack underflow");

        Item item = first.item; 

        first = first.next;

        return item;

    }







    //returns (but does not remove) the item most recently added to this stack.

    public Item peek() {

        if (isEmpty()) throw new ArrayIndexOutOfBoundsException("Stack underflow");

        return first.item;

    }







}




You are supposed to use Junit5 to create a test class with test cases, LinkedStackTest.java, to test the operations of LinkedStack.

Here are some other requirements for the activity:

Create a LinkedStackTest.java and write test cases to test all the operations of LinkedStack.java



Pushing 10000 objects into a stack should not take longer than 5 miliseconds



Pop and peek methods should throw NoSuchElementException
if stack is empty




Provide the list of failing test cases and explain the reason for failure



Resolve the issues by modifying the original class in a separate class LinkedStackFixed.java file and make sure all tests pass.