Zayith

Zayith is a test framework that combines the best of node and the browser.

The Problem

When running in a test framework built on top of node, like Jest, you don't have access to real DOM APIs, like window and document.

Some test frameworks (Jest included) try to get around this by using jsdom, but it has limitations; since there's no layout or rendering engine, you can't test things that rely on:

• What the page looks like (for eg. Visual Regression Testing)
• .getBoundingClientRect()
• document.body.innerText

This is usually solved by running the tests in a real browser, using something like Karma. But, that introduces other limitations:

• You can't use require in your tests, so your tests need to get compiled somehow
• You can't use fs in your tests, so you can't write snapshots or screenshots to disk.

If you want to do something that requires a real DOM as well as require or fs, then you have to write a complex server that ties everything together.

For example, if you want to render individual parts of your application to the DOM, and then perform Visual Regression Testing by taking screenshots of those components, you need to:

• Start a test "server", running in node
• Compile your tests so they can run in a browser (without require)
• Launch a browser, and make it open your compiled tests (via some http server)
• Have the tests communicate with the test server in order to use fs to write screenshots to disk

It's very complicated, and it's a lot to set up.

If there was a test framework that could run code with access to a Real DOM and node APIs, then we wouldn't need any of those things:

• No need for a test server that wraps fs, because you can access fs directly
• No need for test compilation/bundling, because you can use require right in your tests

Zayith is that test framework.

The Solution

When you run your tests in Zayith, you have access to real DOM APIs and all of node's APIs, including require.

Unlike test frameworks built on top of jsdom, the DOM APIs here are real; your tests are running in a real Chromium browser.

But also, unlike test frameworks built on top Karma, the Node APIs here are also real; your tests are running with full access to all node APIs (such as require, fs, etc).

Zayith gives you the best of both worlds.

Installation

First, install @zayith/core and @zayith/cli:

npm install --save-dev @zayith/core @zayith/cli

Then, add the following to your package.json:

"scripts": {
	"zayith": "zayith"
}

Then, run Zayith using npm:

npm run zayith

Usage

By default, Zayith will run against any test files named like *.test.js.

To change this, you can pass glob strings to the zayith CLI:

npm run zayith -- './**/*.spec.js' '!**/node_modules/**'

You can also pass specific filenames:

npm run zayith -- './tests/first.spec.js' './tests/second.spec.js'

For more usage information run npm run zayith -- --help.