tehviking / pretender

A mock server library with a nice routing DSL

Pretender

Pretender is a mock server library in the style of Sinon (but built from microlibs. Because javascript) that comes with an express/sinatra style syntax for defining routes and their handlers.

Pretender will temporarily replace the native XMLHttpRequest object, intercept all requests, and direct them to little pretend service you've defined.

var PHOTOS = {
  "10": {
    id: 10,
    src: 'http://media.giphy.com/media/UdqUo8xvEcvgA/giphy.gif'
  },
  "42": {
    id: 42,
    src: 'http://media0.giphy.com/media/Ko2pyD26RdYRi/giphy.gif'
  }
};

var server = new Pretender(function(){
  this.get('/photos', function(request){
    var all =  JSON.stringify(Object.keys(PHOTOS).map(function(k){return PHOTOS[k]}))
    return [200, {"Content-Type": "application/json"}, all]
  });

  this.get('/photos/:id', function(request){
    return [200, {"Content-Type": "application/json"}, JSON.stringify(FAKE_PHOTOS[request.params.id])]
  });
});

$.get('/photos/12', {success: function(){ ... }})

The Server DSL

The server DSL is inspired by express/sinatra. Pass a function to the Pretender constructor that will be invoked with the Pretender instance as its context. Available methods are get, put, post, 'delete', patch, and head. Each of these methods takes a url pattern and a callback. The callback will be invoked with a single argument (the XMLHttpRequest instance that triggered this request).

If there were dynamic portions of the url, these well be attached to the request object as a params property with keys matching the dynamic portion and values with the matching value from the url.

You must return an array from this handler that includes the http status code, an object literal of response headers and a string body.

var server = new Pretender(function(){
  this.put('/api/songs/:song_id', function(request){
    request // the xhr object
    request.params // {song_id: 'the id passed in the url'}
    request.queryParams // any query params on the request, here just {}

    return [202, {"Content-Type": "application/json"}, "{}"]
  });
});

Using the Native XMLHttpRequest Object for Unhandled Routes

By default, pretender will throw an error if it doesn't know how to handle a route. You can optionally have the browser handle these requests by specifying passthroughUnhandledRequests = true:

var pretender = new Pretender(function(){
  // routes go here
});
pretender.passthroughUnhandledRequests = true;
$.ajax('/something/on/the/server')

This is useful when using asynchronous script loaders such as Require.js.

Clean up

When you're done mocking, be sure to call shutdown() to restore the native XMLHttpRequest object:

var server = new Pretender(function(){
 ... routing ...
});

server.shutdown(); // all done.