import {Stack} from '../src';

describe('Stack', () => {
    let stack: Stack<number>;

    beforeEach(() => {
        stack = new Stack<number>();
    });

    it('should be empty when initialized', () => {
        expect(stack.isEmpty()).toBe(true);
    });

    it('should push elements onto the stack', () => {
        stack.push(1);
        stack.push(2);
        stack.push(3);
        expect(stack.size()).toBe(3);
    });

    it('should peek at the top element without removing it', () => {
        stack.push(1);
        stack.push(2);
        stack.push(3);
        expect(stack.peek()).toBe(3);
        expect(stack.size()).toBe(3);
    });

    it('should pop elements from the stack', () => {
        stack.push(1);
        stack.push(2);
        stack.push(3);
        const poppedElement = stack.pop();
        expect(poppedElement).toBe(3);
        expect(stack.size()).toBe(2);
    });

    it('should return null when popping from an empty stack', () => {
        const poppedElement = stack.pop();
        expect(poppedElement).toBeNull();
    });

    it('should convert the stack to an array', () => {
        stack.push(1);
        stack.push(2);
        stack.push(3);
        const stackArray = stack.toArray();
        expect(stackArray).toEqual([1, 2, 3]);
    });

    it('should clear all elements from the stack', () => {
        stack.push(1);
        stack.push(2);
        stack.push(3);
        stack.clear();
        expect(stack.size()).toBe(0);
        expect(stack.isEmpty()).toBe(true);
    });

    it('should clone the stack', () => {
        stack.push(1);
        stack.push(2);
        const clonedStack = stack.clone();
        expect(clonedStack.size()).toBe(2);
        expect(clonedStack.pop()).toBe(2);
    });
});