@wordpress/jest-console/README.md

# Jest Console

Custom [Jest](https://jestjs.io/) matchers for the [Console](https://developer.mozilla.org/en-US/docs/Web/API/Console)
object to test JavaScript code in WordPress.

This package converts `console.error`, `console.info`, `console.log` and `console.warn` functions into mocks and tracks their calls.
It also enforces usage of one of the related matchers whenever tested code calls one of the mentioned `console` methods.
It means that you need to assert with `.toHaveErrored()` or `.toHaveErroredWith( arg1, arg2, ... )` when `console.error`
gets executed, and use the corresponding methods when `console.info`, `console.log` or `console.warn` are called.
Your test will fail otherwise! This is a conscious design decision which helps to detect deprecation warnings when
upgrading dependent libraries or smaller errors when refactoring code.

## Installation

Install the module:

```bash
npm install @wordpress/jest-console --save-dev
```

**Note**: This package requires Node.js 14.0.0 or later. It is not compatible with older versions.

### Setup

The simplest setup is to use Jest's `setupFilesAfterEnv` config option:

```js
"jest": {
  "setupFilesAfterEnv": [
    "@wordpress/jest-console"
  ]
},
```

### Usage

### `.toHaveErrored()`

Use `.toHaveErrored` to ensure that `console.error` function was called.

For example, let's say you have a `drinkAll( flavor )` function that makes you drink all available beverages.
You might want to check if function calls `console.error` for `'octopus'` instead, because `'octopus'` flavor is really
weird and why would anything be octopus-flavored? You can do that with this test suite:

```js
describe( 'drinkAll', () => {
	test( 'drinks something lemon-flavored', () => {
		drinkAll( 'lemon' );
		expect( console ).not.toHaveErrored();
	} );

	test( 'errors when something is octopus-flavored', () => {
		drinkAll( 'octopus' );
		expect( console ).toHaveErrored();
	} );
} );
```

### `.toHaveErroredWith( arg1, arg2, ... )`

Use `.toHaveErroredWith` to ensure that `console.error` function was called with
specific arguments.

For example, let's say you have a `drinkAll( flavor )` function again makes you drink all available beverages.
You might want to check if function calls `console.error` with a specific message for `'octopus'` instead, because
`'octopus'` flavor is really weird and why would anything be octopus-flavored? To make sure this works, you could write:

```js
describe( 'drinkAll', () => {
	test( 'errors with message when something is octopus-flavored', () => {
		drinkAll( 'octopus' );
		expect( console ).toHaveErroredWith(
			'Should I really drink something that is octopus-flavored?'
		);
	} );
} );
```

### `.toHaveInformed()`

Use `.toHaveInformed` to ensure that `console.info` function was called.

Almost identical usage as `.toHaveErrored()`.

### `.toHaveInformedWith( arg1, arg2, ... )`

Use `.toHaveInformedWith` to ensure that `console.info` function was called with
specific arguments.

Almost identical usage as `.toHaveErroredWith()`.

### `.toHaveLogged()`

Use `.toHaveLogged` to ensure that `console.log` function was called.

Almost identical usage as `.toHaveErrored()`.

### `.toHaveLoggedWith( arg1, arg2, ... )`

Use `.toHaveLoggedWith` to ensure that `console.log` function was called with
specific arguments.

Almost identical usage as `.toHaveErroredWith()`.

### `.toHaveWarned()`

Use `.toHaveWarned` to ensure that `console.warn` function was called.

Almost identical usage as `.toHaveErrored()`.

### `.toHaveWarnedWith( arg1, arg2, ... )`

Use `.toHaveWarneddWith` to ensure that `console.warn` function was called with
specific arguments.

Almost identical usage as `.toHaveErroredWith()`.

## Contributing to this package

This is an individual package that's part of the Gutenberg project. The project is organized as a monorepo. It's made up of multiple self-contained software packages, each with a specific purpose. The packages in this monorepo are published to [npm](https://www.npmjs.com/) and used by [WordPress](https://make.wordpress.org/core/) as well as other software projects.

To find out more about contributing to this package or Gutenberg as a whole, please read the project's main [contributor guide](https://github.com/WordPress/gutenberg/tree/HEAD/CONTRIBUTING.md).

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