What are unit tests and what tools are used for JavaScript unit testing?

Unit tests automatically verify small code units like individual functions or components, catching errors early; in JavaScript, Jasmine, Jest, and Mocha are common frameworks.

import assert from 'node:assert/strict';
import { describe, it } from 'node:test';
import calculateResistance from '../main/resistance.js';

describe('resistance', function () {
  it('calculate for wiring=serial, r1=0, r2=5', function () {
    assert.strictEqual(calculateResistance(0, 5, 'serial'), 5);
  });
});

Popular frameworks:

• Jasmine (jasmine.github.io)
• Jest (jestjs.io)
• Mocha (mochajs.org)

Go deeper:

• Jest — a widely used, zero-config JavaScript testing framework.
• Unit testing (Wikipedia) — why isolating and testing the smallest code units catches errors early.