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',
        }
    );
});