hungry-fetch/README.md

A hungry fetch mock.

# Hungry Fetch

[![Tests](https://github.com/micromata/hungry-fetch/actions/workflows/tests.yml/badge.svg)](https://github.com/micromata/hungry-fetch/actions/workflows/tests.yml) [![npm](https://img.shields.io/npm/v/hungry-fetch.svg)](https://www.npmjs.com/package/hungry-fetch)

Nomnomnom … lets you test your fetch calls.

## What it doesn’t do

*Hungry Fetch* does not polyfill the [Fetch API](https://developer.mozilla.org/en-US/docs/Web/API/Fetch_API). Furthermore it requires `Response` to be available, so you might actually need to [polyfill the Fetch API](https://github.com/github/fetch) before using *Hungry Fetch*.

## How does it work?

*Hungry Fetch* monkey patches `window.fetch` and saves all calls to `fetch(…)` with it’s parameters.

## Installation

```
npm install --save-dev hungry-fetch
```

## Examples

### Swallow and resolve requests

By default *hungryFetch* resolves any request with an undefined response.

```javascript
import hungryFetch from 'hungry-fetch';

test('test network call', () => {
  return fetch('/path/to/nowhere', {
    body: JSON.stringify({
      data: 'I am a body'
    })
  }).then(() => {
    const call = hungryFetch.singleCall();
    expect(call.url).toBe('/path/to/nowhere');
    expect(call.json().data).toBe('I am a body');
  });
});
```

### Mock response

You can mock responses for explicit URLs. You may also use `*` as url matcher to match any URL. Explicit URLs are stronger weighted than the wildcard matcher, so you can specify a default response and add different responses for explicit URLs.

```javascript
import hungryFetch from 'hungry-fetch';

test('test response', () => {
  hungryFetch.mockResponse('/path/to/nowhere', {
    data: 'some data'
  });

  return fetch('/path/to/nowhere').then(response => {
    return response.json();
  }).then(body => {
    expect(body.data).toBe('some data');
  });
});
```


### Advanced response

You can set some parameters of the response with the third argument of `mockResponse(…)`.

```javascript
import hungryFetch from 'hungry-fetch';

test('advanced response', () => {
  hungryFetch.mockResponse('/somewhere', {}, {
    // set custom status code
    status: 204,

    // set custom content type
    contentType: 'plain/text',

    // set additional headers
    headers: {
      'X-MyHeader': 'hello',
    },
  });

  return fetch('/somewhere').then(res => {
    expect(res.status).toBe(204);
    expect(res.headers.get('Content-Type')).toBe('plain/text');
    expect(res.headers.get('X-MyHeader')).toBe('hello');
  });
});
```