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---
title: Write browser DOM tests with Bun and happy-dom
sidebarTitle: DOM tests
mode: center
---
Use [Happy DOM](https://github.com/capricorn86/happy-dom) to write browser tests with Bun's test runner. Happy DOM implements mocked versions of browser APIs like `document` and `location`.
---
Install `@happy-dom/global-registrator`.
```sh terminal icon="terminal"
bun add -d @happy-dom/global-registrator
```
---
This module exports a "registrator" that injects the mocked browser APIs into the global scope.
```ts happydom.ts icon="/icons/typescript.svg"
import { GlobalRegistrator } from "@happy-dom/global-registrator";
GlobalRegistrator.register();
```
---
This file needs to run before any of your test files. That's a job for Bun's built-in [_preload_](/runtime/bunfig#test-preload) option. Create a `bunfig.toml` file in the root of your project (if it doesn't already exist) and add the following lines.
The `./happydom.ts` file should contain the registration code from the previous step.
```toml bunfig.toml icon="settings"
[test]
preload = "./happydom.ts"
```
---
Now `bun test` executes `happydom.ts` before your test files, so you can write tests that use browser APIs.
```ts dom.test.ts icon="/icons/typescript.svg"
import { test, expect } from "bun:test";
test("set button text", () => {
document.body.innerHTML = `<button>My button</button>`;
const button = document.querySelector("button");
expect(button?.innerText).toEqual("My button");
});
```
---
With Happy DOM registered, the test passes.
```sh terminal icon="terminal"
bun test
```
```txt
dom.test.ts:
✓ set button text [0.82ms]
1 pass
0 fail
1 expect() calls
Ran 1 test across 1 file. [125.00ms]
```
---
See the [Happy DOM repo](https://github.com/capricorn86/happy-dom) and [DOM testing](/test/dom).