Simple Yet Powerful Mocking Framework for NodeJs

View the Project on GitHub realistschuckle/nodemock

NodeMock is a very simple to use mocking framework which can be used to mock functions in JavaScript objects. NodeMock creates mock methods in less code with more expressive manner


Besides it's simplicity it supports following features


Node JS can be used with any testing framework. And we've used it with Nodeunit and it's a perfect match. See Examples


npm install nodemock


Load the Module

var nodemock = require("nodemock");

Creating a mock function with taking arguments and return value

var mocked = nodemock.mock("foo").takes(10, [10, 20, 30]).returns(98);, [10, 20, 30]); // this will return 98; //throws execption

Creating a mock with callback support

var mocked = nodemock.mock("foo").takes(20, function(){}).calls(1, [30, 40]);, function(num, arr) {
    console.log(num); //prints 30
    console.log(arr); //prints 40

    When you invoke foo() nodemock will calls the callback(sits in argument index 1 - as specified)
    with the parameters 30 and 40 respectively. 

Controlling callbacks

With the asynchronous nature of NodeJS(and brower with AJAX too) it'll be great if we can control the execution of the callback in the testing environment. And ctrl() of nodemock helps that

var ctrl = {};
var mocked = nodemock.mock('foo').takes(10, function() {}).ctrl(1, ctrl);
//where ever in your codebase
ctrl.trigger(10, 20); // you can call this as many as you want

Add multiple mock functions

var mocked = nodemock.mock("foo").takes(10).returns(30);; //gives 30

mocked.mock("bar").takes(true).returns(40);; // gives 40

Assertion Support

var mocked = nodemock.mock("foo").takes(20);
var mocked = nodemock.mock("bar").takes(40);;;

//check whether what we've defined is actually executed
mocked.assert(); //returns true

Fails when calls any method in the mock object

var mocked =;; //thorws an exception; //throws an exception

Fails when calls some particular method in the mock object

var mocked = nodemock.mock("foo").fail();
mocked.mock("bar").takes(10);; //thorws an exception; //works perfectly

calls a single mocked method, multiple times

var mocked = nodemock.mock("foo").takes(10, 20).times(2);, 20);, 20);

calls a single mocked method, multiple times with different returns

var mocked = nodemock.mock("foo").takes(10, 20).returns(100);
mocked.mock('foo').takes(10, 20).returns(200);, 20); //returns 100, 20); //returns 200

mock a single method more than once

var mocked = nodemock.mock("foo").takes(10, 20);
mocked.mock("foo").takes(20, 30);
mocked.mock("foo").takes(500);, 20);, 30);

//check whether everything has done
mocked.assert(); //returns true

reset the mock

var mocked = nm.mock('foo').returns(100);; //returns 100
mocked.assert(); //returns true


mocked.doo(); //returns 300
mock.assert() //returns true

ignore method

Sometime we need to ignore some methods going through mocking rules. But we need to have those methods but doing nothing.

var mocked = mock.ignore('hello');
mocked.mock('foo').returns(100);; //returns 100
mock.hello(); //do nothing but the method exists

mock.assert(); // return true, assert have nothing to do with ignored methods

API Documentation


var mocked = require('nodemock').mock('foo');
    Creating a object with mock function "foo"

    Used to alter or create a new mock method and add rules to it as usual


mocked.takes(arg1, args2, ...)
    Specify arguments of the function and verify then when calling

    Specify the return value of the function

mocked.calls(callbackPosition, argumentsArray)       
    Calls a callback at the arguments in index `callbackPosition`
    with the arguments specified in the "argumentsArray"

    when using this you've to define a function signature as a callback in the argument list
    for a callback at index 2 .takes() function will be as,
    mocked.takes(10, 20, function(){})
    If calls at very begining afterword any call on the mocked objects will fail
    Otherwise current mock method will fails someone called that. 

    We can rule the mocked method to be called multiple times with same parameters
    Finally we can check that using above assert method;

    Reset all the rules and mocks created. And bring mocked object into a stage when 

it's created

    Ignore Some methods from the mocking behaviour


    Checks whether rules we've defined using other methods were executed.
    If all the rules were executed return true, otherwise false

    Same as the mocked.assert() but throws an execption if rules breaks.