Testamenta

Lightweight, dependency-free test framework with a Jest-like public API. Useful for environments where bundlers and Node.js are not required, it allows you to test JavaScript code directly in the browser via a simple <script> import.

Key Features

• 📖 Jest-like API: Offers a public interface very similar to Jest (with its obvious limitations), making it intuitive for users already familiar with popular testing frameworks.

• 📦 No Setup: Requires no installation or package management—simply import the framework using a script tag.

• ⏳ Async-Aware: Supports asynchronous test execution via async/await.

• 🔍 Mocking and Spying: Built-in support for mock and spy functions and call tracking.

• 📝 Flexible Logging: Outputs results to the console and the DOM.

Getting Started

Copy the testamenta.js file to your project or import it from a CDN unpkg | jsdelivr.

It can also be installed with npm, but it doesn't make much sense having more complete and robust options like Jest.

// test.html

<script type="module">
  import { tests } from 'https://unpkg.com/testamenta';

  tests(['utils', 'plugins'], {
    path: new URL('.', import.meta.url).href, // path to test files
  });
</script>

Create test files named as *.test.js to be properly loaded. Test files use a syntax similar to Jest.

Warning

The call to describe must be awaited to properly run tests sequentially.

import { describe, it, expect } from 'https://unpkg.com/testamenta';

await describe('Math operations', () => {
  it('should add two numbers', () => {
    expect(1 + 2).toBe(3);
  });
});

Both describe and it can be asynchronous and use async/await, and skipped by using the skip modifier.

import { describe, it, expect } from 'https://unpkg.com/testamenta';

await describe('Promises', () => {
  it('should await for a Promise', async () => {
    const value = await new Promise(resolve => {
      setTimeout(() => resolve(1), 1000);
    });
    expect(value).toBe(1);
  });
});

beforeAll and afterAll can be used to setup and clean resource for the hole test suite (tests inside describe).

beforeEach and afterEach can be used to setup and clean up resources before and after each test in a suite. Returned value in beforeEach is passed as parameter to all it functions.

Mocking and spying functions is supported, allowing you to simulate and track function calls during test execution.

import { describe, it, expect, beforeEach, mockFn, spyOn } from 'https://unpkg.com/testamenta';

const openWindow = spyOn(window, 'open');

await describe('Mocking', () => {
  const mock = mockFn();

  beforeEach(() => mock.reset());

  it('should mock a function', () => {
    mock(1, 2);
    mock(3, 4);

    expect(mock)
      .toHaveBeenCalledTimes(2);
      .toHaveBeenCalledWith(1, 2);

    expect(openWindow).toHaveBeenCalled();
  });
})

Assertion

The expect function allows for assertions within test cases. It provides a wide range of built-in matchers for testing various conditions:

• toBe Asserts strict equality.
• toBeTruthy Asserts that a value is truthy.
• toBeBoolean, toBeNumber, toBeString, toBeArray, toBeDate, toBeObject, toBeFunction: Type checks for primitives, objects and functions.
• toHaveLength: Asserts the length of an array or string.
• toContain: Verifies that an array, object or string contains a specific value.
• toHaveBeenCalled, toHaveBeenCalledTimes, toHaveBeenCalledWith: Matchers for verifying mock function behavior.

All matchers can be negated with the not modifier.

Multiple assertions can be chained together.

Extend the expect function to add additional custom matchers to increment testing flexibility.

import { describe, it, expect } from 'https://unpkg.com/testamenta';

expect.extend(({ toBeNumber }) => ({
  toBeEven: value => toBeNumber(value) && value % 2 === 0,
}));

await describe('Custom matchers', () => {
  it('should assert even numbers', () => {
    expect(2).toBeEven();
    expect(3).not.toBeEven();
  });
});

Development

To run in Node, execute npm run dev. Test suite will run in terminal in watch mode and will update on each change.

To run in browser, start a Live Server in VSCode.