data-structures-again/src/stack/stack.test.js

A Javascript library of simple data structures

const Stack = require('./stack')

test('new should initiate stack an empty stack', () => {
    const stack = new Stack()
    expect(stack).not.toBeNull()
})

test('push should push the value at the top of stack', () => {
    const stack = new Stack()
    stack.push(1)
    stack.push(2)
    expect(stack.peek()).toBe(2)
})

test('pop should return undefined if stack is empty', () => {
    const stack = new Stack()
    const data = stack.pop()
    expect(data).toBe(undefined)
})

test('pop should return first element of an non empty stack', () => {
    const stack = new Stack()
    stack.push(1)
    stack.push(2)
    const data = stack.pop()
    expect(data).toBe(2)
})

test('length should return the length of a stack', () => {
    const stack = new Stack()
    stack.push(1)
    stack.push(2)
    expect(stack.length).toBe(2)
})

test('peek should return undefined if stack is empty', () => {
    const stack = new Stack()
    const top = stack.peek()
    expect(top).toBe(null)
})

test('peek should return top element of a non-empty stack', () => {
    const stack = new Stack()
    stack.push(1)
    stack.push(2)
    const top = stack.peek()
    expect(top).toBe(2)
})

test('empty', () => {
    const stack = new Stack()
    expect(stack.empty()).toBe(true)
    stack.push(1)
    stack.push(2)
    const empty = stack.empty()
    expect(empty).toBe(false)
})

test('toString', () => {
    const stack = new Stack()
    stack.push(1)
    stack.push(2)
    expect(stack.toString()).toBe('2,1')
})