TS Nanotest

Bare-bones Typescript test runner. No bells and whistles. Zero-config.

Installation

Install via NPM:

$ npm install --save-dev ts-nanotest

Use it in the test script:

// package.json

{
  // ...
  "scripts": {
    // ...
    "test": "ts-nanotest **/*.test.ts"
  }
}

You can drop **/*.test.ts as it is assumed by default.

Usage

Create a test class as follows:

// cook.test.ts

import { TestCase, TestSuite } from 'ts-nanotest';
import assert from 'assert';

export default class CookTest extends TestSuite {
  override tests(): TestCase[] {
    return [
      this.test('should cook lunch with low calories', () => {
        const lunch = cookLunch();
        assert.equal(lunch.calories, 'low');
      }),
    ];
  }
}

Nanotest does not use global definitions (such as describe and it). No assertion helpers either. assert almost always suffices. You can still use assertion libraries with Nanotest.

Run the tests via NPM script:

$ npm test

... or directly (needs global installation: npm install --global ts-nanotest):

$ ts-nanotest <glob-pattern>...

Hooks

TestSuite contains the following overrideable hooks:

• beforeAll
• afterAll
• beforeEach
• afterEach

All hooks can be async. The after-hooks are always called, even if the test failed.

Example

import { TestCase, TestSuite } from 'ts-nanotest';
import assert from 'assert';

export default class AdvancedCookTest extends TestSuite {
  override async beforeAll() {
    await turnOnTheStove();
  }

  override afterAll() {
    turnOffTheStove();
  }

  override async beforeEach() {
    await buyComponents();
  }

  override afterEach() {
    washTheDishes();
  }

  override tests(): TestCase[] {
    return [
      this.test('should cook a delicious dinner', () => {
        const dinner = cookDinner();
        assert.equals(dinner.salt, 'perfect');
      }),

      this.test('should reject bad taste', async () => {
        const badDish = cookSomethingBad();
        await assert.rejects(async () => {
          await judge.taste(badDish);
        }, BadTasteError);
      }),
    ];
  }
}

Skipping tests

Sometimes you need to temporarily skip some tests during active development. To do so, use this.skip() instead of this.test().

Why

Testing should be fast, easy, light, and manageable. These characteristics are especially important if you are practising test-driven development (TDD).

Fast. Most projects should have all their tests run in a few seconds.

Easy. Writing tests should be as easy as writing production code. No learning curve.

Light. Test packages (not the tests themselves) should have almost no effect on the size of a project.

Manageable. Test packages should interface with but be isolated from the production environment.

To achieve this, Nanotest includes only the bare minimum.