# chai-fetch-mock

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> Chai plugin for fetch-mock library

A set of [Chai](http://chaijs.com/) assertions for [fetch-mock](https://github.com/wheresrhys/fetch-mock), a mocking library for `fetch()` and [isomorphic-fetch](https://www.npmjs.com/package/isomorphic-fetch).

## Installation

This library depends on:

```
"peerDependencies": {
  "chai": "3.x || 4.x",
  "fetch-mock": "5.1.x || 6.x"
}
```

**Note:** fetch-mock 6.0 is only compatible with Node.js 7 or greater.

Install those, and then install:

```bash
npm install chai-fetch-mock
```

## Usage

**Note:** if you want to use this plugin with other Chai plugins that use a similar vocabulary—such as sinon-chai, which also has a `called` assertion—apply chai-fetch-mock _last_. chai-fetch-mock's methods will only kick in when an assertion calls the `route()` method.

```js
import chai from 'chai';
import chaiFetchMock from 'chai-fetch-mock';
import fetchMock from 'fetch-mock';

// Call conflicting plugins before
// chai.use(sinonChai)
chai.use(chaiFetchMock);

describe('test', () => {
  before(() => fetchMock.get('/cats', { cats: 5 }))

  it('calls fetch', () => {
    return fetch('/cats').then(() => {
      expect(fetchMock).route('/cats').to.have.been.called;
    });
  });

  after(() => fetchMock.restore());
});
```

## API

### route(value)

Sets up an assertion to check calls to a matcher with the name `value`. This is either the URL of the route, or the custom name of the route. Use this before any other fetch-mock assertion.

```js
// Default name
fetchMock.get('*', {});
expect(fetchMock).route('*');

// Custom name
fetchMock.get(/.*/, {}, { name: 'all' });
expect(fetchMock).route('all');
```

This function on its own only asserts that the mock route exists.

### called

Asserts that `fetch()` was used to call a specific route at least once.

```js
expect(fetchMock).route('*').to.have.been.called;
expect(fetchMock).route('*').to.not.have.been.called;
```

This method can be chained to the ones below, allowing you to check if a route was called *and* if it was called with specific properties in one assertion.

### args(value)

Asserts that the arguments of last call to `fetch()` to a specific route deeply equal `value`.

```js
getCat(1).then(() => {
  expect(fetchMock).route('/cats/get').to.have.been.called.with.args(['/cats/get', { id: 1 }]);
});
```

### args(value)

Asserts that the URL of last call to `fetch()` to a specific route equals `value`.

```js
getDoggo(2).then(() => {
  expect(fetchMock).route('/doggos/get').to.have.been.called.with.url('/doggos/get/2');
});
```

### options(value)

Asserts that the options of last call to `fetch()` to a specific route deeply equal `value`.

```js
getDoggo(2).then(() => {
  expect(fetchMock).route('/doggos/get').to.have.been.called.with.options({ mode: 'same-origin' });
});
```

## License

MIT © [Geoff Kimball](http://geoffkimball.com)