faussaire

Faussaire v0.2

Lightweight javascript library to mock network request for testing purposes

Status

This project is still an idea and probably needs further improvements. Suggests and PR are welcome.

Installation

npm install --save-dev faussaire

Overview

Faussaire is library aiming to mock an API in tests. As said Robert C. Martin in the Ruby Midwest 2011 Conf, tests should be completely independant from your webservices, your database or whatever kind of IO device / Network implementation. Following this idea, one should be able to use a fake API with a similar behavior of any server.

Faussaire implements a simple interface allowing you to create route with URLs and method, and to put a controller to return a response object. Using the fetch() method you can easily make calls and simulate a response.

Usage Example

Basic usage

You can register a route using faussaire.Route.

import faussaire, {Route, Controller, Response} from 'faussaire';

faussaire
  .route(Route({
    template: "http://foo.com",
    methods: ["GET"],
    controller: Controller({
      run: (params, options) => {
        return Response({
          data: {
            foo: params.query.foo,
            bar: params.query.bar
          },
          status: 200,
          statusText: "OK"
        })
      }
    })
  }));

const response = faussaire.fetch("http://foo.com", "GET", {
  params: {
    foo: "bar",
    bar: "qux"
  }
});

The params object

Usually, all controller's method can access the params. It is an object composed of :

• query : holds GET parameters (?foo=1&bar=2)
• request : holds POST parameters
• route : holds routing request (see below)

Templating

You can give a simple URL to a template, but if you want to build complex URL matching, you can use Regex.

faussaire.route(
  Route({
    template: "http://foo.com/(\\w+)/access",
    methods: ["GET"],
    ...
  })
);

You can also match routing point with values and get them in the parameters using brackets.

faussaire.route(
  Route({
    template: "http://foo.com/posts/{id}",
    methods: ["GET"],
    ...
  })
);

You will find the ID in params.route.id.

Authentication

You can as well pre-authenticate the user sending a request by defining an authenticate(params, options) in the controller. It should return a token in case of success and it will be stored in the options object as options.token. If the authentication fail, there wont be any token object in options.

import faussaire, {Route, Controller, Response} from 'faussaire';

faussaire
  .route(Route({
    template: "http://foo.com/ressouce",
    methods: ["GET"],
    controller: Controller({
      authenticate: function(params, options){
        if(params.apikey){
          return {
            apikey: params.query.apikey,
            at: Date.now(),
            expire: //...
          }
        }
      },
      run: (params, options) => {
        if(options.token){
          return Response({
            status: 200,
            statusText: "OK"
          })
        }

        return Response({
          status: 403,
          statusText: "Wrong credentials"
        })
      }
    })
  }));

const response = faussaire.fetch("http://foo.com", "GET", {
  params: {
    foo: "bar",
    bar: "qux"
  }
});

API

faussaire.fetch: (url, method, params) => response (Object)

The equivalent of a standard fetch.

faussaire.route: (route) => faussaire

Adds a route to Faussaire.

Route: (Object) => Object

Return a route with :

• template : usually a URL or a Regex. If the URL matches the template, the controller starts processing.
• methods : an array of HTTP methods to handle (basically ["GET"])
• controller : a Controller type object processing the request.

Controller: (Object) => Object

Return a controller with :

• run(params, options): this function must return a response. The options holds a method entry and might have additionnal data passed by authenticate for example.
• authenticate(params, options'): must return an object representing an authentication token if the request hold enough information to recognize the user, or return nothing/undefined.

Response: (Object) => Object

Return a basic HTTP response with :

• data : the body's response
• status : the HTTP code
• statusText : the response header
• headers : a list of headers (like Location)

Usage in Production

You might want to make your own Fetch interface using Faussaire to automate switching between network fetching and local fetching. This is how it can be implemented :

import fetch from 'fetch';
import faussaire from 'faussaire';

const request = (url, method, params) => {
  if(process.env.NODE_ENV === "test"){
    return faussaire(url, method, params);
  }

  return fetch(url, method, params);
};

export default request;

Pros and Cons

Pros

• Easy to use and to mock routing & stores
• Pushes you to use proper testing habits
• Allows you to work offline

Cons

• Not implementing Promise yet
• Makes you rewrite an API, only for testing and offline development, which is a cost of time
• Young and therefore lacks possibilities
• Must be updated as your backend evolves

Evolutions

• Handling Promises
• Proper means to authenticate
• Handle data storage and standard functions to avoid repeating schemas (like CRUD)
• Simulate timeout if wanted (you probably don't in testing but might be useful for offline support)
• Get closer to what a network request flow should look alike (in term of headers, etc)
• Add Listeners to look for a certain template and then call subscribers when it happen, and/or pass additional options to the controller (like Symfony Events Listeners)
• Create an additional library to manage storage and simulate a database
• Start an idiomatic-faussaire tutorial to use it properly

Related

• faussaire-util, bundle utilitary functions for faussaire