superagent-mock

superagent plugin allowing to simulate HTTP calls by returning data fixtures based on the requested URL.

See this post to know why we use superagent-mock at Bedrock Streaming.

Installation

Install with npm: npm install superagent-mock

Install with yarn: yarn add superagent-mock

Requirements

node >= 8.0 superagent >= ^3.6.0

Usage

First, you have to define the URLs to mock in a configuration file:

// ./superagent-mock-config.js file
module.exports = [
  {
    /**
     * regular expression of URL
     */
    pattern: 'https://domain.example(.*)',

    /**
     * returns the data
     *
     * @param match array Result of the resolution of the regular expression
     * @param params object sent by 'send' function
     * @param headers object set by 'set' function
     * @param context object the context of running the fixtures function
     */
    fixtures: function (match, params, headers, context) {
      /**
       * Returning error codes example:
       *   request.get('https://domain.example/404').end(function(err, res){
       *     console.log(err); // 404
       *     console.log(res.notFound); // true
       *   })
       */
      if (match[1] === '/404') {
        throw new Error(404);
      }

      /**
       * Checking on parameters example:
       *   request.get('https://domain.example/hero').send({superhero: "superman"}).end(function(err, res){
       *     console.log(res.body); // "Your hero: superman"
       *   })
       */

      if (match[1] === '/hero') {
        if(params['superhero']) {
          return 'Your hero:' + params['superhero'];
        } else {
          return 'You didnt choose a hero';
        }
      }


      /**
       * Checking on headers example:
       *   request.get('https://domain.example/authorized_endpoint').set({Authorization: "9382hfih1834h"}).end(function(err, res){
       *     console.log(res.body); // "Authenticated!"
       *   })
       */

      if (match[1] === '/authorized_endpoint') {
        if(headers['Authorization']) {
          return 'Authenticated!';
        } else {
          throw new Error(401); // Unauthorized
        }
      }

      /**
       * Cancelling the mocking for a specific matched route example:
       *   request.get('https://domain.example/server_test').end(function(err, res){
       *     console.log(res.body); // (whatever the actual server would have returned)
       *   })
       */

      if (match[1] === '/server_test') {
        context.cancel = true; // This will cancel the mock process and continue as usual (unmocked)
        return null;
      }

      /**
       * Delaying the response with a specific number of milliseconds:
       *   request.get('https://domain.example/delay_test').end(function(err, res){
       *     console.log(res.body); // This log will be written after the delay time has passed 
       *   })
       */

      if (match[1] === '/delay_test') {
        context.delay = 3000; // This will delay the response by 3 seconds
        return 'zzZ';
      }

      /**
       * Mocking progress events:
       *   request.get('https://domain.example/progress_test')
       *     .on('progress', function (e) { console.log(e.percent + '%'); })
       *     .end(function(err, res){
       *       console.log(res.body); // This log will be written after all progress events emitted 
       *     })
       */

      if (match[1] === '/progress_test') {
        context.progress = {
          parts: 3,               // The number of progress events to emit one after the other with linear progress
                                  //   (Meaning, loaded will be [total/parts])
          delay: 1000,            // [optional] The delay of emitting each of the progress events by ms 
                                  //   (default is 0 unless context.delay specified, then it's [delay/parts])
          total: 100,             // [optional] The total as it will appear in the progress event (default is 100)
          lengthComputable: true, // [optional] The same as it will appear in the progress event (default is true)
          direction: 'upload'     // [optional] superagent adds 'download'/'upload' direction to the event (default is 'upload')
        };
        return 'Hundred percent!';
      }
    },

    /**
     * returns the result of the GET request
     *
     * @param match array Result of the resolution of the regular expression
     * @param data  mixed Data returns by `fixtures` attribute
     */
    get: function (match, data) {
      return {
        body: data
      };
    },

    /**
     * returns the result of the POST request
     *
     * @param match array Result of the resolution of the regular expression
     * @param data  mixed Data returns by `fixtures` attribute
     */
    post: function (match, data) {
      return {
        status: 201
      };
    }
  },
  ...
];

Then use the plugin:

// ./server.js file
var request = require('superagent');
var config = require('./superagent-mock-config');

// Before tests
var superagentMock = require('superagent-mock')(request, config);

...

// After tests
superagentMock.unset();

Supported methods

All request methods are supported (get, put, post, etc.).

Each request method mock have to be declared in the config file. Otherwise, the callback method is used.

Logging

You can monitor each call, that has been intercepted by superagent-mock or not, by passing a callback function at initialization.

// ./server.js file
var request = require('superagent');
var config = require('./superagent-mock-config');

var logger = function(log)  {
  console.log('superagent call', log);
};

// Before tests
var superagentMock = require('superagent-mock')(request, config, logger);

...

// After tests
superagentMock.unset();

The callback function will be called with an object containing the following informations

• data : data used with superagent.send function
• headers : array of headers given by superagent.set function
• matcher : regex matching the current url which is defined in the provided config
• url : url which superagent was called
• method : HTTP method used for the call
• timestamp : timestamp of the superagent call
• mocked : true if the call was mocked by superagent mock, false if it used superagent real methods

Development scripts

To run units tests: yarn test.

To check code style: yarn lint.

To build code: yarn build.

Credits

Developped by the Cytron Team of Bedrock Streaming. Tested with Jest.

License

superagent-mock is licensed under the MIT license.