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This is not a mocking library. This module allows you to require a module and pass mocks for its dependencies.

Dependencies that are not passed will be solved normally.

This module uses vm.runInNewContext and is heavily inspired by this answer in stackoverflow answer.


npm install mockuire


Given a file like this one foo.js:

var path = require("path");
module.exports = function(a, b){
    return path.join(a, b, "burbujas");

then we can test as follows:

  var mockuire = require("mockuire")(module);
  exports.test = function (test) {
    //this is the "mock" of the module path  
    var mockedPath = { 
      join: function() { 
          return, 0).join("!"); 
    //now I "mockuire" the module under test with the mocked path 
    var foo = mockuire("./fixture/foo", { path: mockedPath });
    //let's see if it works: 
    result = foo( "a", "b" );
    test.equal( result, "a!b!burbujas" );

You have to pass the module in order to fallback to the module require when needed.

Private members

Two new methods will be added to the instance returned by mockuire.

Given a file like private.js:

var count = 1;
function ping() {
  return 'pong';
} = function() {
  return ++count;
module.exports.testPing = function() {
  return ping();

method: _private_get(name)

It allows you to get the value of a private variable:

it ('should be able to get value of a private evariable', function() {
  var mockuire = require("mockuire")(module);
  var private = mockuire("./fixture/private");
  assert.equal(private._private_get('count'), 1);

method: _private_set(name, value)

It allows you to set the value of a private variable:

it ('should be able to get value of a private evariable', function() {
  var mockuire = require("mockuire")(module);
  var private = mockuire("./fixture/private");
  private._private_set('count', 10);
  assert.equal(, 11);

You can also set private members in the same moment you pass mocks for its dependencies

it('should be able to set value of a private evariable', function() {
  var mockuire = require("../lib/index")(module);
  var mocks = {};
  var props = {
    count: 100
  var private = mockuire("./fixture/private", mocks, props);
  assert.equal(, 101);

method: _private_fn(name, [mock])

It allows you to get a reference to a private function:

it('should be able to get and invoke a private function', function() {
  var mockuire = require("mockuire")(module);
  var private = mockuire("./fixture/private");
  var ping = private._private_fn('ping');
  assert.equal(typeof ping, 'function');
  assert.equal(ping(), 'pong');

You can also set a mock function:

function helloWorld() {
  return "Hello world!";
var mockuire = require("mockuire")(module);
var private = mockuire("./fixture/private");
var pingMocked = private._private_fn('ping', helloWorld);
it('mocked function should invoke the mock function', function() {
  assert.equal(pingMocked(), 'Hello world!');
it ('module\'s functions should invoke mock function', function() {
  assert.equal(private.testPing(), 'Hello world!');
it('mocked function has a \'func\' property pointing to the original function', function() {
  assert.equal(pingMocked.func(), 'pong');
// mocked function has a method to reset to the original function. 
it('mocked function should be replaced by the original one.', function() {
  assert.equal(pingMocked(), 'pong');
it ('module\'s functions should invoke the original function', function() {
  assert.equal(private.testPing(), 'pong');

Contrib - run tests

npm test



  1. Friendly with modules of code coverage, like istanbul.

Breaking changes

Changes for 2.x

  1. Does not accept compilers on constructor. The version 2.x relies on the infrastrucuture of nodejs in order to load and compile a module.


MIT License