Cannot use require in my mocha tests with karma runner via gulp

Question

I hit the same problem with my second project again. Sadly I have to post mostly every config file here to show you enough information - so don't be scared ;)

I'm using the following to unit test:

• gulp
• karma
• mocha

---

gulpfile.js

// including plugins
var gulp = require('gulp')
    , uglify = require("gulp-uglify")
    , concat = require('gulp-concat')
    , clean = require('gulp-clean')
    , open = require('gulp-open')
    , babel = require("gulp-babel")
    , copy = require("gulp-copy")
    , mocha = require('gulp-mocha');

var Server = require('karma').Server;


gulp.task('tests', function(done) {
    Server.start({
        configFile: __dirname + '/karma.config.js',
        singleRun: true
    }, function() {
        done();
    });
});

karma.config.js

module.exports = function(config) {
    config.set({
        browsers: ['Chrome'],
        frameworks: ['mocha'],
        files: [
            './target/src/heritage.guard.js',
            './tests/dummies/dummies.babel.js',
            './tests/heritageguardtests.js'
        ],

        plugins:[
            'karma-chrome-launcher',
            'karma-mocha'
        ]
    });
};

heritageguardtest.js

var assert = require('assert');

var classDummy = new ClassDummy();
var superClassDummy = new SuperClassDummy();

describe('HeritageGuard Tests', function () {
    describe('getSuperClassName', function () {
        it('should return the name of the super class as String', function () {

            var superClassName = HeritageGuard.getSuperClassName(classDummy);
            assert.equal(superClassName, "SuperClassDummy");
        });
    });
});

Output of Gulp "tests" task

[09:51:39] Using gulpfile c:\...\...\...\...\JavaScriptProjects\HeritageGuard\gulpfile.js
[09:51:39] Starting 'tests'...
06 03 2016 09:51:39.512:WARN [karma]: Port 9876 in use
06 03 2016 09:51:39.514:WARN [karma]: Port 9877 in use
06 03 2016 09:51:39.515:INFO [karma]: Karma v0.13.21 server started at http://localhost:9878/
06 03 2016 09:51:39.519:INFO [launcher]: Starting browser Chrome
06 03 2016 09:51:48.390:INFO [Chrome 49.0.2623 (Windows 10 0.0.0)]: Connected on socket /#aVMDjm22W8-g3Z_8AAAA with id 44639779
Chrome 49.0.2623 (Windows 10 0.0.0) ERROR
  Uncaught ReferenceError: require is not defined
  at c:/.../.../.../.../JavaScriptProjects/HeritageGuard/tests/heritageguardtests.js:8


[09:51:48] Finished 'tests' after 9.06 s

Process finished with exit code 0

---

As you can read require is not defined but without using var assert = require('assert'); in my mocha test file I cannot use the assertion library == no way to test.

So how did anybody before solved this issue? I can't find any solution for either using another way to get the assertion library to work (without require) nor getting require to work within the testfile.

Answer 1

Karma isn't a server-side testing framework, so you don't have NodeJS's modules like fs or assert.

Karma will simply inject the test/frameworks scripts directly into the page. It doesn't use any sort of bundling/module pattern.

You need to include an assertion library using Karma (If you want the "expect" syntax, have a look at chai.js) by adding it to the files: entry in karma.conf.js, and then it should be available to you globally, without the need for requireing anything.