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Node js unit testing: mocking requires dependency

I am having trouble writing a unit test for the following installation as a jira.js file (in a node.js module):

var rest = require('restler'); // https://www.npmjs.com/package/restler module.exports = function (conf) { var exported = {}; exported.getIssue = function (issueId, done) { ... rest.get(uri).on('complete', function(data, response) { ... }; return exported; };

Now I want to write unit test for my getIssue function. A "restler" is a REST client through which I make JIRA API REST calls to get a JIRA problem through my code.

So, in order to be able to test createIssue (..), I want to be able to make fun of the "rest" var in my Jasmine unit tests.

How can I mock this method? Please give me some pointers so that I can go forward. I tried using rewire, but I failed.

This is what still does not work for me (i.e. the getIssue method turns out to be undefined):

 var rewire = require("rewire"); var EventEmitter = require('events').EventEmitter; var emitter = new EventEmitter(); var cfg = require("../../../config.js").Configuration; var jiraModule = rewire("../lib/jira")(cfg); var sinon = require("sinon"); var should = require("should"); // https://github.com/danwrong/restler var restMock = { init : function () { console.log('mock initiated'+JSON.stringify(this)); }, postJson : function (url, data, options) { console.log('[restler] POST url='+url+', data= '+JSON.stringify(data)+ 'options='+JSON.stringify(options)); emitter.once('name_of_event',function(data){ console.log('EVent received!'+data); }); emitter.emit('name_of_event', "test"); emitter.emit('name_of_event'); emitter.emit('name_of_event'); }, get : function (url, options) { console.log('[restler] GET url='+url+'options='+JSON.stringify(options)); }, del : function (url, options) { console.log('[restler] DELETE url='+url+'options='+JSON.stringify(options)); }, putJson : function (url, data, options) { console.log('[restler] PUT url='+url+', data= '+JSON.stringify(data)+ 'options='+JSON.stringify(options)); } }; var cfgMock = { "test" : "testing" }; jiraModule.__set__("rest", restMock); jiraModule.__set__("cfg", cfgMock); console.log('mod='+JSON.stringify(jiraModule.__get__("rest"))); describe("A suite", function() { it("contains spec with an expectation", function() { restMock.init(); restMock.postJson(null, null, null); console.log(cfg.jira); // the following method turns out to be undefined but when i console.log out the jiraModule, i see the entire code outputted from that file jiraModule.getIssue("SRMAPP-130", function (err, result) { console.log('data= '+JSON.stringify(result)); }); expect(true).toBe(true); }); });

If someone can direct me on how to mock "rest" requires addiction and unit test, this method will be very useful.

Also, how do I make fun of the 'conf' passed to module.exports?

thanks

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1 answer

You can use proxyquire or mockery to mute / mock dependencies.

In the example below, I used proxyquire . Hope this helps.

 /* ./src/index.js */ var rest = require('restler'); module.exports = function (conf) { var exported = {}; exported.getIssue = function (issueId, done) { var uri = ''; var reqObj = ''; var service = { auth : '' }; rest.postJson(uri, reqObj, service.auth).on('complete', function(data, response) { done(data, response); }); }; return exported; }; 
 /* ./test/index.js */ var proxyquire = require('proxyquire'); var assert = require('chai').assert; var restlerStub = { postJson: function() { return { on: function(event, callback) { callback('data', 'response'); } } } } var index = proxyquire('../src/index', {'restler': restlerStub})(); describe('index', function() { it('should return the desired issue', function(done) { var issue = index.getIssue('issueId', function(data, response) { assert.equal(data, 'data'); assert.equal(response, 'response'); done(); }) }); }); 
 /* ./package.json */ { "scripts": { "test": "mocha" }, "dependencies": { "restler": "^3.4.0" }, "devDependencies": { "chai": "^3.4.1", "mocha": "^2.3.4", "proxyquire": "^1.7.3" } }
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