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    This is a installable sailsjs hook that lets you rewire sails components, when sails is lifted in test environment.

    Often during testing you need to stub certain functions inside your sails models/controllers/services, for example a function that makes http calls.

    sails-hook-rewire uses the rewire module to replace components already loaded by sails, with their rewired versions.


    npm install sails-hook-rewire --save


    List components you want rewired, in config/rewire.js
     * Configuration to list which sails components to rewire.
     * You can rewire models, polices, adapters, hooks, blueprints, and responses.
     * You can also choose to have models and services rewired in the global object. Sails only injects models and services
     * in the global obejct.
     * @type {Object} 
    module.exports.rewire = {
      // List services to be rewired
      services: [
          name: 'FileService',
          global: true    // replace the global FileService with the rewired version
          name: 'FetchService',
          global: false   // don't replace the global FetchService with the rewired version
      // List controllers to be rewired
      controllers: [
          name: 'FileController'
          name: 'DNSLookUpController',
          global: true    // this does nothing as controllers are not injected into the global object by sails
    Rewire your components

    Suppose you have a service, FileService, that depends on the fs module, and you want to stub fs.readFile method in the service. Since the service has already been rewired, all you need to do is stub

    var expect = require('expect.js'),
    describe('Tests for FileService', function () {
      before(function () {
        fileServiceRevert = FileService.__set__({
          fs: {
            readFile: function (filename, options, callback) {
              var response = {
                err: null,
                data: undefined
              callback = typeof options === 'function' && options || callback || function () {};
              // Return an error if filename matches error, eg /var/www/jsons/error.json
              filename.match(/error/) && (response.err = new Error('Error reading file'));
              // Return a valid JSON string if file matches valid, eg /var/www/jsons/valid.json
              filename.match(/.+\/valid/) && ( = '{"valid": true}');
              // Return an invalid JSON string if file matches invalid, eg /var/ww/jsons/invalid.json
              filename.match(/.+\/invalid/) && ( = '{"invalid": true;');
              return callback(response.err,;
      after(function () {
        // Revert the rewiring
      it('handles read error', function (done) {
        FileService.fetchJSONFromFile('/var/www/jsons/error.json', function (err, data) {
          expect(err.error instanceof Error);
          return done();
      it('handles invalid json', function (done) {
        FileService.fetchJSONFromFile('/var/www/jsons/invalid.json', function (err, data) {
          expect(err.error instanceof Error);
          return done();
      it('returns a json if file has valid json', function (done) {
        FileService.fetchJSONFromFile('/var/www/jsons/valid.json', function (err, data) {
          return done();
    Run tests

    When running tests, ensure that sails is lifted in the test environment. You can do this by either,

    • Setting NODE_ENV to test before the tests are run
    export NODE_ENV=test;
    npm test;
    unset NODE_ENV;
    • Passing the environment to sails while loading in a test bootstrap.
    var Sails = require('sails'),
    before(function (done) {
        environment: 'test'
        // other setting overrides
      function (err, server) {
        if (err) { return done(sails); }
        sails = server;
        return done(null, sails);
    after(function (done) {

    Optionally, if you wish to lift your server in test mode, you can pass the environment as an option to sails lift

    sails lift --environment=test

    For more examples of how to test sails components with rewire, check out the tests for this module.

    This project is licensed under the Apache 2.0 License.

    For contributing, please check the contributing guidelines.

    Made with ❤️ by Postman


    npm i sails-hook-rewire

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