fakerest

FakeRest

Intercept XMLHttpRequest to fake a REST server based on JSON data. Use it on top of Sinon.js to test JavaScript REST clients on the browser side (e.g. single page apps) without a server.

Usage

<script src="/path/to/FakeRest.min.js"></script>
<script src="/path/to/sinon.js"></script>
<script type="text/javascript">
// initialize fake REST server and data
var restServer = new FakeRest.Server();
restServer.init({
    'authors': [
        { id: 0, first_name: 'Leo', last_name: 'Tolstoi' },
        { id: 1, first_name: 'Jane', last_name: 'Austen' }
    ],
    'books': [
        { id: 0, author_id: 0, title: 'Anna Karenina' },
        { id: 1, author_id: 0, title: 'War and Peace' },
        { id: 2, author_id: 1, title: 'Pride and Prejudice' },
        { id: 3, author_id: 1, title: 'Sense and Sensibility' }
    ]
});
// use sinon.js to monkey-patch XmlHttpRequest
var server = sinon.fakeServer.create();
server.respondWith(restServer.getHandler());

// Now query the fake REST server
var req = new XMLHttpRequest();
req.open("GET", "/authors", false);
req.send(null);
console.log(req.responseText);
// [
//    {"id":0,"first_name":"Leo","last_name":"Tolstoi"},
//    {"id":1,"first_name":"Jane","last_name":"Austen"}
// ]

var req = new XMLHttpRequest();
req.open("GET", "/books/3", false);
req.send(null);
console.log(req.responseText);
// {"id":3,"author_id":1,"title":"Sense and Sensibility"}

var req = new XMLHttpRequest();
req.open("POST", "/books", false);
req.send(JSON.stringify({ author_id: 1, title: 'Emma' }));
console.log(req.responseText);
// {"author_id":1,"title":"Emma","id":4}

// restore native XHR constructor
server.restore();
</script>

Tip: The fakerServer provided by Sinon.js is available as a standalone library, without the entire stubbing framework. Simply add the following bower dependency:

devDependencies: {
  "sinon-server": "http://sinonjs.org/releases/sinon-server-1.14.1.js"
}

Installation

FakeRest is available through npm and Bower:

# If you use Bower
bower install fakerest --save-dev
# If you use npm
npm install fakerest --save-dev

REST Flavor

FakeRest uses a standard REST flavor, described below.

• GET /foo returns a JSON array. It accepts three query parameters: filter, sort, and range. It responds with a status 200 if there is no pagination, or 206 if the list of items is paginated. The response contains a mention of the total count in the Content-Range header.

    GET /books?filter={author_id:1}&sort=['title','desc']&range=[0-9]
  
    HTTP 1.1 200 OK
    Content-Range: items 0-1/2
    Content-Type: application/json
    [
      { id: 3, author_id: 1, title: 'Sense and Sensibility' },
      { id: 2, author_id: 1, title: 'Pride and Prejudice' }
    ]
  

  The filter param must be a serialized object litteral describing the criteria to apply to the search query.

    GET /books?filter={author_id:1} // return books where author_id is equal to 1
    HTTP 1.1 200 OK
    Content-Range: items 0-1/2
    Content-Type: application/json
    [
      { id: 2, author_id: 1, title: 'Pride and Prejudice' },
      { id: 3, author_id: 1, title: 'Sense and Sensibility' }
    ]
  
    // array values are possible
    GET /books?filter={id:[2,3]} // return books where id is in [2,3]
    HTTP 1.1 200 OK
    Content-Range: items 0-1/2
    Content-Type: application/json
    [
      { id: 2, author_id: 1, title: 'Pride and Prejudice' },
      { id: 3, author_id: 1, title: 'Sense and Sensibility' }
    ]
  
    // use the special "q" filter to make a full-text search on all text fields
    GET /books?filter={q:'and'} // return books where any of the book properties contains the string 'and'
  
    HTTP 1.1 200 OK
    Content-Range: items 0-2/3
    Content-Type: application/json
    [
      { id: 1, author_id: 0, title: 'War and Peace' },
      { id: 2, author_id: 1, title: 'Pride and Prejudice' },
      { id: 3, author_id: 1, title: 'Sense and Sensibility' }
    ]
  
    // use _gt, _gte, _lte, or _lt suffix on filter names to make range queries
    GET /books?filter={price_lte:20} // return books where price is less than or equal to 20
    GET /books?filter={price_gt:20} // return books where price is greater than 20
  
    // when the filter object contains more than one property, the criteria combine with an AND logic
    GET /books?filter={published_at_gte:'2015-06-12',published_at_lte:'2015-06-15'} // return books published between two dates
  

  The sort param must be a serialized array litteral defining first the property used for sorting, then the sorting direction.

    GET /author?sort=['date_of_birth','asc']  // return authors, the oldest first
    GET /author?sort=['date_of_birth','desc']  // return authors, the youngest first
  

  The range param defines the number of results by specifying the rank of the first and last result. The first result is #0.

    GET /books?range=[0-9] // return the first 10 books
    GET /books?range=[10-19] // return the 10 next books
  

• POST /foo returns a status 201 with a Location header for the newly created resource, and the new resource in the body.

POST /books
{ author_id: 1, title: 'Emma' }

HTTP 1.1 201 Created
Location: /books/4
Content-Type: application/json
{ "author_id": 1, "title": "Emma", "id": 4 }

• GET /foo/:id returns a JSON object, and a status 200, unless the resource doesn't exist

GET /books/2

HTTP 1.1 200 OK
Content-Type: application/json
{ id: 2, author_id: 1, title: 'Pride and Prejudice' }

• PUT /foo/:id returns the modified JSON object, and a status 200, unless the resource doesn't exist
• DELETE /foo/:id returns the deleted JSON object, and a status 200, unless the resource doesn't exist

If the REST flavor you want to simulate differs from the one chosen for FakeRest, no problem: request and response interceptors will do the conversion (see below).

Usage and Configuration

// initialize a rest server with a custom base URL
var restServer = new FakeRest.Server('http://my.custom.domain');
restServer.toggleLogging(); // logging is off by default, enable it
// Set all JSON data at once - only if identifier name is 'id'
restServer.init(json);
// modify the request before FakeRest handles it, using a request interceptor
// request is {
//     url: '...',
//     headers: [...],
//     requestBody: '...',
//     json: ..., // parsed JSON body
//     queryString: '...',
//     params: {...} // parsed query string
// }
restServer.addRequestInterceptor(function(request) {
    var start = (request.params._start - 1) || 0;
    var end = request.params._end !== undefined ? (request.params._end - 1) : 19;
    request.params.range = [start, end];
    return request; // always return the modified input
});
// modify the response before FakeRest sends it, using a response interceptor
// response is {
//     status: ...,
//     headers: [...],
//     body: {...}
// }
restServer.addResponseInterceptor(function(response) {
    response.body = { data: response.body, status: response.status };
    return response; // always return the modified input
});
// enable batch request handler, i.e. allow API clients to query several resourecs into a single request
// see [Facebook's Batch Requests philosophy](https://developers.facebook.com/docs/graph-api/making-multiple-requests) for more details.
restServer.batchUrl('/batch');

// you can create more than one fake server to listen to several domains
var restServer2 = new FakeRest.Server('http://my.other.domain');
// Set data collection by collection - allows to customize the identifier name
var authorsCollection = new RestServer.Collection([], '_id');
authorsCollection.addOne({ first_name: 'Leo', last_name: 'Tolstoi' }); // { _id: 0, first_name: 'Leo', last_name: 'Tolstoi' }
authorsCollection.addOne({ first_name: 'Jane', last_name: 'Austen' }); // { _id: 1, first_name: 'Jane', last_name: 'Austen' }
// collections have autoincremented identifier but accept identifiers already set
authorsCollection.addOne({ _id: 3, first_name: 'Marcel', last_name: 'Proust' }); // { _id: 3, first_name: 'Marcel', last_name: 'Proust' }
restServer2.addCollection('books', authorsCollection);
// collections are mutable
authorsCollection.updateOne(1, { last_name: 'Doe' }); // { _id: 1, first_name: 'Jane', last_name: 'Doe' }
authorsCollection.removeOne(3); // { _id: 3, first_name: 'Marcel', last_name: 'Proust' }

var server = sinon.fakeServer.create();
server.autoRespond = true;
server.respondWith(restServer.getHandler());
server.respondWith(restServer2.getHandler());

Development

# Install dependencies
make install
# Watch source files and recompile dist/FakeRest.js when anything is modified
make watch
# Run tests
make test
# Build minified version
make build

License

FakeRest is licensed under the MIT Licence, sponsored by marmelab.