**Easy dependency injection for node.js unit testing**.

[](http://travis-ci.org/jhnns/rewire)

[](https://david-dm.org/jhnns/rewire)

[](https://coveralls.io/r/jhnns/rewire)

[](https://www.gittip.com/peerigon/)

rewire adds a special setter and getter to modules so you can modify their behaviour for better unit testing. You may

- inject mocks for other modules or globals like`process`

If you want to use rewire also on the client-side take a look at[client-side bundlers](https://github.com/jhnns/rewire#client-side-bundlers)

[](http://travis-ci.org/jhnns/rewire)

[](https://david-dm.org/jhnns/rewire)

[](https://coveralls.io/r/jhnns/rewire)

[](https://www.gittip.com/peerigon/)

[](https://npmjs.org/package/rewire)

<br />

Installation

<br />

Examples

Introduction

Imagine you want to test this module:

var fs=require("fs"),

path="/somewhere/on/the/disk";

Now within your test module:

var rewire=require("rewire");

var myModule=rewire("../lib/myModule.js");

myModule.__get__("path");// = '/dev/null'

This allows you to mock everything in the top-level scope of the module, like the fs-module for example. Just pass the variable name as first parameter and your mock as second.

This allows you to mock everything in the top-level scope of the module, like the fsmodule for example. Just pass the variable name as first parameter and your mock as second.

var fsMock= {

});

You can also setdifferent variables with one call.

You can also setmultiple variables with one call.

myModule.__set__({

});

`__set__` returns a function which reverts the changes introduced by this particular`__set__` call

var revert=myModule.__set__("port",3000);

revert();

For your convenience you can also use the`__with__` method which reverts the given changes after it finished.

myModule.__with__({

port:3000

})(function () {

});

The`__with__` method is also aware of promises. If a thenable is returned all changes stay until the promise has either been resolved or rejected.

myModule.__with__({

port:3000

})(function () {

returnnewPromise(...);

}).then(function () {

});

**Difference to require()**<br>

<br />

##API

API

Returns a rewired version of the module found at`filename`. Use`rewire()` exactly like`require()`.

-*filename*: <br/>

Path to the module that shall be rewired. Use it exactly like require().

-*name*: <br/>

Name of the variable to set. The variable should be global or defined with`var` in the top-leve scope of the module.

-*value*: <br/>

The value to set.

###rewiredModule.&#95;&#95;set&#95;&#95;(env)

-*env*: <br/>

Takes all keys as variable names and sets the values respectively.

Returns the private variable with the given`name`.

###rewiredModule.&#95;&#95;get&#95;&#95;(name):value

Returns theprivate variable.

Returnsa function which - when being called - sets`obj`, executesthegiven`callback` and reverts`obj`. If`callback` returns a promise,`obj` is only reverted after the promise has been resolved or rejected. For your convenience the returned function passes the received promise through.

<br />