[**@cprussin/jest-config v3.1.4**](../README.md)

***

# index

This package contains a set of jest configs that set up runners for running
unit tests, integration tests, eslint, and prettier.

# Installing

Use the package manager of your choice to install:

- **npm**: `npm install --save-dev @cprussin/jest-config`
- **pnpm**: `pnpm add -D @cprussin/jest-config`
- **yarn**: `yarn add -D @cprussin/jest-config`

# Usage

1. Set up your `jest.config.js`, for example:

```js
export { base as default } from "@cprussin/jest-config";
```

2. Run `run-jest --color always` to run format checks, lint checks, unit tests, and
   integration tests, or use `--selectProjects` to run a [subset of
   checks](#md:projects).

3. Add scripts to your `package.json` if you'd like. For instance:

```json
{
  "scripts": {
    "test:format": "run-jest --color always --selectProjects format",
    "test:integration": "run-jest --color always --selectProjects integration",
    "test:lint": "run-jest --color always --selectProjects lint",
    "test:unit": "run-jest --color always --coverage --selectProjects unit"
  }
}
```

# Projects

Configurations exported with this package will set up the following jest
projects:

- `format`: Check code style with prettier using `jest-runner-prettier`.
- `integration`: Tests that run out of the `integration-tests` directory.
  Functionally not much different than `unit`, but you can have a separate
  configuration, different pipeline dependencies, etc.
- `lint`: Run eslint checks using `jest-runner-eslint`.
- `unit`: Need I say more?

Running `run-jest --color always` will run all four projects. You can run a subset of the
projects using jest's `--selectProjects` argument, as usual.

# Options

If you need to, you can extend or wrap the configs generated here by calling
the config you want and passing an object as an argument that describes your
modifications. The object can have any combination of the following keys:

- `format`: Specify extensions or wrappers for the `format` project.
- `global`: Specify extensions or wrappers for the top-level jest config.
- `integration`: Specify extensions or wrappers for the `integration` project.
- `lint`: Specify extensions or wrappers for the `lint` project.
- `unit`: Specify extensions or wrappers for the `unit` project.

The value for each of those keys should be an object containing either or
both of `config`, an object whose values will be spread into the relevant
project or global config, and `wrapper`, a function that should take the
config and return a promise containing the final config. For example:

```js
import { base } from "@cprussin/jest-config";

export default base({
  global: {
    wrapper: async (oldGlobalConfig) => doSomethingAsyncWith(oldGlobalConfig),
    config: {
      passWithNoTests: true,
    },
  },
  unit: {
    wrapper: async (oldUnitConfig) => doSomethingAsyncWith(oldUnitConfig),
  },
  format: {
    config: {
      testPathIgnorePatterns: ["foo/*"],
    },
  },
});
```

Note that the extensions will be spread _before_ calling the wrapper (so the
values in the `config` option will be present in the argument to the
`wrapper`).

## Functions

- [base](functions/base.md)