Karma can't load webpack

Question

I'm getting this error;

16 07 2015 13:03:52.741:WARN [preprocess]: Can not load "webpack"!
   Error: Can not resolve circular dependency! (Resolving: preprocessor:webpack -> webpackPlugin -> preprocessor:webpack)

My karma.conf looks like;

var webpack = require('webpack');

module.exports = function (config) {
  config.set({
    browsers: [ 'Chrome' ], //run in Chrome
    singleRun: true, //just run once by default
    frameworks: [ 'mocha' ], //use the mocha test framework
    files: [
      'tests.webpack.js' //just load this file
    ],
    preprocessors: {
      'tests.webpack.js': [ 'webpack', 'sourcemap' ] //preprocess with webpack and our sourcemap loader
    },
    reporters: [ 'dots' ], //report results in this format
    webpack: { //kind of a copy of your webpack config
      devtool: 'inline-source-map', //just do inline source maps instead of the default
      module: {
        loaders: [
          { test: /\.js$/, loader: 'babel-loader' }
        ]
      }
    },
    webpackServer: {
      noInfo: true //please don't spam the console when running in karma!
    }
  });
};

and tests.webpack.js

var context = require.context('./src', true, /-test\.js$/); //make sure you have your directory and regex test set correctly!
context.keys().forEach(context);

I do have karma and karma-webpack installed.

Any ideas ?

Answer 1

Something has changed in the latest versions of karma-* projects. I have got the same issue as I installed everything latest. Now I tried exactly the versions here and it worked out.

Answer 2

I had a similar error but the post referenced in the accepted solution did not work for me. If you're looking for alternatives, read below!

---

I was seeing the following error message:

WARN [preprocess]: Can not load "webpack"!
TypeError: Object [object Object] has no method 'refreshFiles'
at Plugin.notifyKarmaAboutChanges (/Users/abhandaru/workspace/source/macaw-campaigns/node_modules/karma-webpack/index.js:108:15)
at Plugin.<anonymous> (/Users/abhandaru/workspace/source/macaw-campaigns/node_modules/karma-webpack/index.js:72:9)
at Tapable.applyPlugins (/Users/abhandaru/workspace/source/macaw-campaigns/node_modules/webpack/node_modules/tapable/lib/Tapable.js:26:37)

I found this solution on a Github issue:

https://github.com/webpack/karma-webpack/issues/65

Here is are the updated lines in my package.json:

"karma": "^0.13.3",
"karma-chrome-launcher": "^0.2.0",
"karma-jasmine": "^0.3.6",
"karma-webpack": "^1.7.0",

Hope this helps.

Answer 3

You should upgrade "karma" and "karma-webpack" packages. Had similar exception, upgrading to next versions solved this:

"karma": "0.13.18",
"karma-webpack": "1.7.0"