docs/40-testing/10-vitest.md
---
title: Vitest
description: How we automate our tests using Vitest. Vitest is a testing framework designed for unit testing.
---
How we automate our tests using [Vitest](https://vitest.dev/).
Vitest is a testing framework designed for unit testing.
## Installation
```bash
npm install -D vitest
```
## File Name
In the same directory as the file of the code to be tested is in, write test code in a file named [filename of the code to be tested].test.ts.
## Options
Change the files to be included in the test run.
```ts:vite.config.ts
export default defineConfig({
test: {
include: ['src/**/*.{test,spec}.{js,ts}'],
coverage: {
all: true,
include: ['src/**/*.ts'],
exclude: [
'src/**/+*.ts',
'src/app.d.ts',
'src/hooks.server.ts',
'src/scripts/create_git_branch.ts',
],
reporter: ['lcov', 'text'],
},
},
})
```
[Configuring Vitest >](https://vitest.dev/config/)
## Scripts
We have prepared the following scripts to execute Vitest.
```json:package.json
{
"scripts": {
"test:unit": "vitest",
"test:unit:run": "vitest run",
"coverage": "vitest run --coverage",
}
}
```
## VSCode Extension
Use the [VSCode Extension](./vscode-workspace-extensions#testing) for testing.
## Sample Code
```ts:[talk]src/lib/general/valid_id.test.ts
import { expect, it } from 'vitest'
import { ValidId } from './valid_id'
it('1', () => {
expect(new ValidId(1).id).toEqual(1)
})
```
When checking thrown errors:
```ts:[talk]src/lib/general/valid_id.test.ts
import { expect, it } from 'vitest'
import { ValidId } from './valid_id'
it('NaN', () => {
expect(() => new ValidId(NaN)).toThrow('id is not a number')
})
```
## In-source testing
```ts:[talk]src/lib/locale/i18n.ts
if (import.meta.vitest) {
const { expect, it } = import.meta.vitest
it('get_initial_app_locale_code', () => {
expect(get_initial_locale_code()).toBe('en-US')
})
}
```
```ts:vite.config.ts
export default defineConfig({
define: {
'import.meta.vitest': 'undefined',
},
})
```
```json:tsconfig.json
{
"compilerOptions": {
"types": ["vitest/importMeta"]
}
}
```
[Here is the official documentation >](https://vitest.dev/guide/in-source.html)
## Use test.each when there are multiple test data
- Define the type of your test specifications using the `type` keyword.
- Prepare your test data in an array format.
- Use `test.each` to execute tests on each item in your array of test data.
```ts:src/lib/docs/markdown.test.ts
type Spec = {
name: string
path: string
description: string
}
const specs: Spec[] = [
{
name: 'About',
path: './docs/10-company-information/20-about.md',
description:
'sinProject Inc. is an software development company in Osaka, Japan. We primarily use SvelteKit and TypeScript, but also work with other programming languages and frameworks.',
},
{
name: 'Events',
path: './docs/10-company-information/40-events.md',
description: 'Here are some of the events organized by sinProject.',
},
]
it.each(specs)('generate_page_content($name)', async (spec) => {
const { name, path, description, content } = spec
const result = await Markdown.generate_page_content(path)
expect(result.title).toBe(name)
expect(result.description).toBe(description)
})
```