Tests in Node.js 20 - built-in test runner

node_test_runner.js

import { test, mock } from 'node:test';
import assert from 'node:assert';
import fs from 'node:fs';

test('first test', (t) => {
  assert.strictEqual(8, 8);
});

test('second test', (t) => {
  assert.strictEqual(9, 9);
});

mock.method(fs, 'readFile', async () => 'Lorem ipsum');

test('third test', async (t) => {
  assert.strictEqual( await fs.readFile('anyfile'), 'Lorem ipsum' );
});