Karma throws jasmineRequire is not defined error with webpack and jasmine

Question

So I'm having this error while trying to run karma with jasmine and webpack:

Uncaught ReferenceError: jasmineRequire is not defined at node_modules/karma-jasmine/lib/boot.js:116

I thought it was my project so I decided to create a new one and here's the following configuration for it.

I'm having the same problem with this configuration. Has anyone an idea?

For webpack:

const path = require("path");

module.exports = {
    entry: './src/source1.js',
    output: {
        path: path.resolve("./dist")
    }
}

For karma:

const webpackConfig = require("./webpack.config");
module.exports = function(config) {
  config.set({
    basePath: '',
    frameworks: ['jasmine'],
    webpack: webpackConfig,
    files: [
      'test/t1.js'
    ],
    exclude: [
    ],
    preprocessors: {
      "**/*.js": ["webpack"]
    },
    reporters: ['progress'],
    port: 9876,
    colors: true,
    logLevel: config.LOG_INFO,
    autoWatch: true,
    browsers: ['Chrome'],
    singleRun: false,
    concurrency: Infinity
  })
}

I have a test/t1.js file like so:

// import { add } from "../src/source1";

function add(x, y) {
    return x + y;
}

describe("source1", () => {
    describe("add", () => {
        it("adds 41 + 1", () => {
            expect(add(41, 1)).toBe(42);
        });
    });
});

And here's my package.json file:

{
  "name": "projects",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "",
  "license": "ISC",
  "devDependencies": {
    "jasmine-core": "^2.6.2",
    "karma": "^1.7.0",
    "karma-chrome-launcher": "^2.1.1",
    "karma-jasmine": "^1.1.0",
    "karma-webpack": "^2.0.3",
    "webpack": "^2.5.1"
  }
}

Answer 1

I know how to fix this, I just don't know why it works. If anyone can answer that, I'd appreciate.

The fix is, instead of having the following config in karma.conf.js

preprocessors: {
  "**/*.js": ["webpack"]
},

I now have:

preprocessors: {
  "test/**/*.js": ["webpack"]
},