Mocha test of React component which uses System.js to handle css import

Question

How can I make mocha run with System.js handling all require/import statements? I have a React component which does an import of CSS file. When running on browser System.js gets loaded and it's plugin-css handles import of css files. But when running as a Mocha unit test import of a css file causes Mocha to crash.

import '../../../dist/css/common/NavBar.css!';

throws error Error: Cannot find module '../../../dist/css/common/NavBar.css!'

Does anyone have a similar test setup up and running ?

score 1 · Answer 1 · answered Nov 19 '15 at 22:36

You're probably gonna need to start using Karma and a plugin for System.js

https://www.npmjs.com/package/karma-systemjs

Here's a karma.conf.js to get you started:

module.exports = function(config) {
    config.set({

        browsers: [ 'Chrome' ],

        singleRun: false,

        frameworks: ['mocha', 'sinon', 'systemjs'],

        plugins: [
            'karma-systemjs'
            'karma-chrome-launcher',
            'karma-chai',
            'karma-mocha',
            'karma-sourcemap-loader',
            'karma-spec-reporter',
            'karma-mocha-reporter',
            'karma-sinon'
        ],

        files: [
            'test/bootstrap.js'
        ],

        reporters: [ 'spec' ],

        systemjs: {
            // Path to your SystemJS configuration file 
            configFile: 'app/system.conf.js',

                // Patterns for files that you want Karma to make available, but not loaded until a module requests them. eg. Third-party libraries. 
                    serveFiles: [
                'lib/**/*.js'
            ],

                // SystemJS configuration specifically for tests, added after your config file. 
                // Good for adding test libraries and mock modules 
                    config: {
                paths: {
                    'angular-mocks': 'bower_components/angular-mocks/angular-mocks.js'
                }
            }
        }

    });
};

and in test/bootstrap.js perhaps this:

//test/bootstrap.js
//put this in your test directory (include it with your tests or test recursively)

// setup globals
chai = require('chai');
chai.should();
chai.use(require('chai-things'));
assert = require('chai').assert;
expect = require('chai').expect;
should = require('chai').should;
React = require('react/addons');
global.TestUtils = React.addons.TestUtils;
ReactTools = require('react-tools');
reactStub = React.createClass({
                        displayName: 'StubClass',
                        mixins: [],
                        render: function() {
                            return null;
                        }
                    });


// setup
before(function(){

});
beforeEach(function(){

});

// teardown
afterEach(function() {

});
after(function(){

});

// include all the tests
var context = require.context('./', true, /-test\.js$/);
context.keys().forEach(context);

I had mocha running in nodejs itself, please checkout my answer. But I think in the longer run I will move to this karma setup. Seems like karma is better maintained and has good support for coverage and all. — Jithin, Nov 20 '15 at 00:42

score 1 · Accepted Answer · answered Nov 20 '15 at 00:40

I got it working in nodejs itself. I just had to stub out imports to css files. Rest of stuff babel handles. This is my require file which mocha uses.

process.env.BABEL_DISABLE_CACHE = 1;

require('babel-core/register')({
  'optional': [
    'es7.classProperties'
  ],
  'resolveModuleSource': function (source) {
    if (source.indexOf('dist/css') !== -1) {
      return '../../../test/css-dummy.js';
    }
    return source;
  },
  'blacklist': []
});

Mocha test of React component which uses System.js to handle css import

2 Answers2