tests/capitalize.test.js

+import { test } from 'node:test';

+import assert from 'node:assert';

+import { capitalize } from '../src/capitalize.js';

+test('capitalize normal string', () => {

+ assert.strictEqual(capitalize('hello'), 'Hello');

+});

+test('capitalize empty string returns empty string', () => {

+ assert.strictEqual(capitalize(''), '');

+});

+test('capitalize non-string input throws TypeError', () => {

+ assert.throws(

+ () => capitalize(123),

+ {

+ name: 'TypeError',

+ message: 'Input must be a string',

+ }

+ );

+});