![Picture of Unit Tests](/assets/images/blog/2023/04/16/00-cover.jpg)

## Intro 

I've been singing the praises of the T3 Stack for building modern web apps of late. Whilst awesome and I 
recommend it strongly to anybody starting a new React+TypeScript app it does have what could be called a serious omission. It does not configure any testing libraries at all. 

I think I understand why this is the case. I hate configuring tests in front-end land at the best of times. There are so many different plugins and configurations to add. They are a constantly moving target and the ones you use get deprecated and replaced. If that wasn't bad enough there are multiple ways to configure the them, between using `.json` files (my preference) and configuring using `.ts|.js` files. It's never what I would call a nice experience, I wish it was done for me by T3 but you can't be mad at them for staying away from this whole mess. 

I have had to configure tests recently and it was exactly as frustrating to configure this time as it was all the previous times so I thought let's write a blog and break it down so we can come back to this in 6 months time when we inevitably have to do it again!

I've got it down to a small collection of additional packages that need to be installed and just a couple of config files (`.json`).  I like to use dedicated `.json` files for these bits of config rather than a code file `.ts|.js`. I just think it makes everything easier to reason about. I also prefer them to be dedicated `.json` files rather than just dumping all config into `package.json`. I've seen some wild version of this file over the years and it's just horrible in my humble opinion.

## Configuration - Packages

First of all if you haven't already got a project you can generate a new T3 stack app using the following:

```bash
npm create t3-app@latest
```

Nex to install additional packages into `package.json` for`Babel`, `React Testing Library` and `Jest`, run the following commands:

### Babel

```bash
npm install --save-dev @babel/preset-env @babel/preset-react @babel/preset-typescript
```

[babel-preset-env](https://babeljs.io/docs/babel-preset-env)

[babel-preset-react](https://babeljs.io/docs/babel-preset-react)

[babel-preset-typescript](https://babeljs.io/docs/babel-preset-typescript)

### Testing Library

```bash
npm install --save-dev @testing-library/react @testing-library/user-event @testing-library/jest-dom
```

[@testing-library/react](https://www.npmjs.com/package/@testing-library/react)

[@testing-library/user-event](https://www.npmjs.com/package/@testing-library/user-event)

[@testing-library/jest-dom](https://www.npmjs.com/package/@testing-library/jest-dom)

### Jest

```bash
npm install --save-dev jest jest-environment-jsdom
```

[jest](https://www.npmjs.com/package/jest)

[jest-environment-jsdom](https://www.npmjs.com/package/jest-environment-jsdom)

## Configuration - Configs

### Babel 

Add a configuration file in the root of the project for Babel and paste in the following content:

File: `babel.config.json`
```json
{
  "presets": [
      "@babel/preset-env",
      "@babel/preset-react",
      "@babel/preset-typescript"
  ]
}
```

### Jest

Add a configuration file in the root of the project for Jest and paste in the following content:

File: `jest.config.json`
```json
{
    "testEnvironment": "jsdom"
}
```

### Package JSON

Find the `scripts` section and `add` the following: 

File: `package.json`

```json
 "scripts": {
    "test": "jest"
  }
```

Your `scripts` section will already include other options. I removed them here for brevity.

## Example 

Now that everything's configured let's build a simple `<Greeting>` component and add a couple of tests.    

File: `/components/greeting/greeting.tsx`

```javascript
import React from "react"
import { 
    type FC
} from "react"

type Props = {
    name: string
}

const Greeting: FC<Props> = ({ name }) => {

    let greeting = `Hello ${ name }!`;

    if (name.length === 0)
        greeting = "I'm sorry I didn't catch your name?"

    return <h1>{ greeting }</h1>
}
export default Greeting
```

File: `/components/greeting/greeting.spec.tsx`

```javascript
import React from "react";
import {render, screen} from "@testing-library/react"
import "@testing-library/jest-dom"
import Greeting from "./greeting"

test("name supplied - displays personalised greeting", async () => {
  // ARRANGE
  render(<Greeting name="liam" />)

  // ACT
  await screen.findByRole("heading")

  // ASSERT
  expect(screen.getByRole("heading")).toHaveTextContent("Hello liam")
})

test("name not supplied - asks for name", async () => {
  // ARRANGE
  render(<Greeting name="" />)

  // ACT
  await screen.findByRole("heading")

  // ASSERT
  expect(screen.getByRole("heading")).toHaveTextContent("I'm sorry I didn't catch your name?")
})
```

If we run the tests using `npm run test` and everything is configured properly then the output should show 2x passing tests. 

![picture showing test results](/assets/images/blog/2023/04/16/01-tests.png)

## Outro

I don't know what you think but that seemed liked a lot of work and a lot of crap just to get going, just so we can add tests of questionable value. 🤫
  
Surely we can come up with a better way than this? 

If you liked this post I am planning to release another post with some actual tests that will cover testing [tRPC](https://trpc.io/) with [Mock Service Worker](https://mswjs.io/docs/api) or more specifically [msw-trpc](https://www.npmjs.com/package/msw-trpc). 

If you haven't already subscribed to my [RSS](https://www.liam-reilly.info/feed.xml) feed, please do to make you don't miss it!

You can download the source code for this post

TESTING T3 STACK APPS

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