npm package: @patoudss/jest-schematic
Description: Schematic to add jest to an Angular CLI project
Author: Briebug
Latest version: 3.2.0

# Jest Angular Schematic

This schematic will configure Angular to execute unit tests with Jest for single projects or workspaces.

Fork of the https://github.com/briebug/jest-schematic until this pull request is merged : https://github.com/briebug/jest-schematic/pull/79

[![npm (scoped)](https://img.shields.io/npm/v/@patoudss/jest-schematic.svg)](https://www.npmjs.com/package/@patoudss/jest-schematic)

## Usage 🚀

```shell
ng add @patoudss/jest-schematic
```

- install [Jest](https://facebook.github.io/jest/), types and a [builder](https://github.com/just-jeb/angular-builders/tree/master/packages/jest)
- add Jest configuration files
- remove Karma & Jasmine along with their configuration files

### Optionally: install globally

```shell
npm install -g @patoudss/jest-schematic
```

Then in an Angular CLI project run

```shell
ng g @patoudss/jest-schematic:add
```

![jest-schematic-demo-500](docs/jest-schematic-demo-500.gif)

## Issues 🧐

If you're experiencing issues when trying to run your tests with Jest, please view the documentation for the [builder](https://github.com/just-jeb/angular-builders/tree/master/packages/jest) which uses [jest-preset-angular](https://github.com/thymikee/jest-preset-angular#troubleshooting).

A common issues involves library dependencies. For example if your app depends on `NgRx` you'll need to tell Jest to compile the sources [explicitly](https://github.com/thymikee/jest-preset-angular#adjust-your-transformignorepatterns-whitelist) by appending it to the `transformIgnorePatterns` property in the `jest.config.js` file.

```js
module.exports = {
  transformIgnorePatterns: ['node_modules/(?!(jest-test|@ngrx))'],
};
```

Issues with this schematic can be filed [here](https://github.com/briebug/jest-schematic/issues/new/choose).

## Learning Resources 📚

- [Unit Testing Angular With Jest](https://medium.com/@ole.ersoy/unit-testing-angular-with-jest-b65888ff33f6)

## Development 🛠

### Getting started

Clone or fork the repo and install the dependencies with Yarn

```shell
yarn
```

### Test schematic changes against a sandbox app

When running locally, schematic changes will be applied to a test app in the `/sandboxes` directory. `/sandboxes` contain a single app repo and a workspace repo with an application and library.

Run the following when a schematic change is made to test:

```bash
// runs against /sandboxes/single-app
yarn test single

// runs against /sandboxes/workspace
yarn test workspace
```

⚠ **Be careful not to check in changes to the sandbox directory unless necessary.** ⚠

### Reset sandboxes to their version controlled state

This will reset the sandboxes to their `HEAD` commit and remove un-tracked files.

```shell
yarn reset
```

### Test schematics against a local project

- run `yarn build` to compile the schematic in watch mode
- open another shell, cd into the local repo you want to run the schematic against, and run `yarn link @patoudss/jest-schematic`. This assumes you've run `yarn link` in this repo on your machine.
  - this will symlink the projects so that the Jest schematic command runs from you're local filesystem
- in the local repo you want to run the schematic against, run `ng g @patoudss/jest-schematic:add`

### Dev tips

For faster developing, find and comment out the following line to avoid npm installing dependencies

```ts
context.addTask(new NodePackageInstallTask());
```