@vue/cli-plugin-unit-jest
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unit-jest plugin for vue-cli
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# @vue/cli-plugin-unit-jest
> unit-jest plugin for vue-cli
## Injected Commands
- **`vue-cli-service test:unit`**
Run unit tests with Jest. Default `testMatch` is `<rootDir>/(tests/unit/**/*.spec.(js|jsx|ts|tsx)|**/__tests__/*.(js|jsx|ts|tsx))` which matches:
- Any files in `tests/unit` that end in `.spec.(js|jsx|ts|tsx)`;
- Any js(x)/ts(x) files inside `__tests__` directories.
Usage: `vue-cli-service test:unit [options] <regexForTestFiles>`
All [Jest command line options](https://facebook.github.io/jest/docs/en/cli.html) are also supported.
## Debugging Tests
Note that directly running `jest` will fail because the Babel preset requires hints to make your code work in Node.js, so you must run your tests with `vue-cli-service test:unit`.
If you want to debug your tests via the Node inspector, you can run the following:
```bash
# macOS or linux
node --inspect-brk ./node_modules/.bin/vue-cli-service test:unit --runInBand
# Windows
node --inspect-brk ./node_modules/@vue/cli-service/bin/vue-cli-service.js test:unit --runInBand
```
## Configuration
Jest can be configured via `jest.config.js` in your project root, or the `jest` field in `package.json`.
## Installing in an Already Created Project
```bash
vue add unit-jest
```
## Transform dependencies from `/node_modules`
By default, jest doesn't transform anything from `/node_modules`.
Since jest runs in node, we also don't have to transpile anything that uses modern ECMAScript features as Node >=8 already supports these features, so it's a sensible default. cli-plugin-jest also doesn't respect the `transpileDependencies` option in `vue.config.js` for the same reason.
However, we have (at least) three cases where we do need to transpile code from `/node_modules` in jest:
1. Usage of ES6 `import`/`export` statements, which have to be compiled to commonjs `module.exports`
2. Single File Components (`.vue` files) which have to be run through `vue-jest`
3. Typescript code
To do this, we need to add an exception to the `transformIgnorePatterns` option of jest. This is its default value:
```javascript
transformIgnorePatterns: ['/node_modules/']
```
We have to add exceptions to this pattern with a RegExp negative lookahead:
```javascript
transformIgnorePatterns: ['/node_modules/(?!name-of-lib-o-transform)']
```
To exclude multiple libraries:
```javascript
transformIgnorePatterns: ['/node_modules/(?!lib-to-transform|other-lib)']
```