We Replaced Jest With node:test in 12 Services — Here's What Broke and What Didn't

After months of using Jest for unit testing, we decided to take the plunge and migrate to the built-in node:test runner. The results were surprising, with some features working seamlessly and others requiring significant rework. In this post, we'll share our journey and the lessons we learned along the way.

Introduction to node:test

The node:test runner is a built-in testing framework that comes with Node.js. It's designed to be fast, efficient, and easy to use. Here's an example of a simple test using node:test:

import { test } from 'node:test';

import { Command } from '@aws-sdk/client-lambda';