Testing JavaScript – Unit & Integration

Popular test frameworks:

• Jest – zero‑config, snapshot testing, mocking.
• Mocha + Chai – flexible BDD/TDD style.
• Cypress – end‑to‑end browser testing.

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Example: Jest unit test

// sum.js
export const sum = (a,b) => a + b;
// sum.test.js
import {sum} from './sum.js';
test('adds two numbers', () => {
  expect(sum(1,2)).toBe(3);
});

Run with npm test.

Example: Cypress basic test

describe('My App',()=>{
  it('shows hello message',()=>{
    cy.visit('/');
    cy.contains('h1','Hello');
  });
});