Using Node's built-in test runner with Turborepo

It takes only five easy steps to add unit tests to a Turborepo monorepo. No external testing frameworks, such as Jest or Mocha, are needed.

1. Add tsx at the monorepo’s root level to run TypeScript code without issues related to different module systems:

npm add --dev tsx

2. Add a test task to turbo.json:

{
  ...
  "tasks": {
    "test": {
      "outputs": []
    },
    ...
  },
  ...
}

3. Add a test script in every package.json where necessary:

  "scripts": {
    ...
    "test": "tsx --test"
  },

4. Add a test script into the monorepo's root package.json:

  "scripts": {
   ... 
   "test": "turbo run build && turbo run test"
  }

The build step is optional, but it ensures the project compiles successfully before running tests. Alternatively, add a dependency on the build step in turbo.json.

5. That is it. Now add your first test using the built-in Node.js test runner functionality:

add.ts

  export function add(a: number, b: number) {
    return a + b;
  };

add.test.ts

import assert from 'node:assert/strict';
import { describe, it } from 'node:test';
import { add } from './add.ts';

describe('Test addition', () => {
  it('should add two positive numbers', () => {
    assert.equal(add(2, 2), 4);
  });

  it('should add two negative numbers', () => {
    assert.equal(add(-2, -2), -4);
  });
});

Finally, give it a try by running:

npm run test