Come up with test cases for the RPN (RPNTest. java) to ensure it works correctly. A good way to test the RPN valuator by sending tokens one at a time to evaluate() or by calling the evaluateLine() passing a full text line. There should a test for all special cases, for example division by 0, or pop and empty stack, etc.
How could I come up with an assertEquals method for each of the methods in RPNTest.java? Below is what I have so far.
RPNTest.java
public class RPNTest
{
// A Linked List Node
class Node
{
int data; // integer data
Node next; // pointer to the next node
}
class Stack
{
private Node top;
private int nodesCount;
public Stack()
{
this.top = null;
this.nodesCount = 0;
}
// Utility function to add an element `x` to the stack
public void push(int x) // insert at the beginning
{
// allocate a new node in a heap
Node node = new Node();
// check if stack (heap) is full. Then inserting an element would
// lead to stack overflow
if (node == null) {
System.out.println("Heap Overflow");
return;
}
System.out.println("Inserting " + x);
// set data in the allocated node
node.data = x;
// set the .next pointer of the new node to point to the current
// top node of the list
node.next = top;
// update top pointer
top = node;
// increase stack's size by 1
this.nodesCount += 1;
}
// Utility function to check if the stack is empty or not
public boolean isEmpty()
{
return top == null;
}
// Utility function to return the top element of the stack
public int peek()
{
// check for an empty stack
if (isEmpty()) {
System.out.println("The stack is empty");
System.exit(-1);
}
return top.data;
}
// Utility function to pop a top element from the stack
public int pop() // remove at the beginning
{
// check for stack underflow
if (isEmpty()) {
System.out.println("Stack Underflow");
System.exit(-1);
}
// take note of the top node's data
int top = peek();
System.out.println("Removing " + top);
// decrease stack's size by 1
this.nodesCount -= 1;
// update the top pointer to point to the next node
this.top = (this.top).next;
return top;
}
// Utility function to return the size of the stack
public int numElements()
{
return this.nodesCount;
}
}
class Main
{
public static void main(String[] args)
{
Stack stack = new Stack<E>();
stack.push(1);
stack.push(2);
stack.push(3);
System.out.println("The top element is " + stack.peek());
stack.pop();
stack.pop();
stack.pop();
if (stack.isEmpty()) {
System.out.println("The stack is empty");
}
else {
System.out.println("The stack is not empty");
}
}
}
}
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