How can I get Karma + Webpack to find the module?

I want to run my tests on a bunch of modules after webpack has combined them together through the Karma test runner, but whenever I run my tests Karma says,

"Error: Cannot find module "hello.js" at http://localhost:9877/base/src/hello.spec.js?d301966ffc1330826574d9d8fff5a644c3390c68:47"

I have a spec file:

var a = require('hello.js');

describe("a test test", function() {

  it("humperdink test", function() {
    expect(a).toEqual('humperdink');
  }); //end it

}); //end describe

hello.js is this:

var a = 'humperdink';

module.exports = a;

Both of these files are in the same folder.

My karma.conf.js is:

module.exports = function (config) {
  config.set({
    frameworks: ['jasmine'],
    files: [
      'src/**/*.js',
      'tests/**/*.spec.js'
    ],
    preprocessors: {
      'tests/**/*.spec.js': ['webpack'],
      'src/**/*.js' : ['webpack']
    },
    browsers: ['PhantomJS'],
    webpack: {
      entry: './src/hello.spec.js',
      output: {
        filename: 'bundle.js'
      }
    },
    webpackMiddleware: {
      noInfo: true
    }
  })
};

Currently my devDependencies installed are

"devDependencies": {
    "jasmine-core": "^2.3.4",
    "jshint": "^2.8.0",
    "karma": "^0.13.15",
    "karma-jasmine": "^0.3.6",
    "karma-jshint-preprocessor": "0.0.6",
    "karma-phantomjs-launcher": "^0.2.1",
    "karma-webpack": "^1.7.0",
    "phantomjs": "^1.9.19",
    "sinon": "^1.17.2",
    "webpack": "^1.12.9"

How do I get Karma to find the hello.js module?

I've tried changing the spec file's first line to things like

require('hello.js');

or

require('./hello.js');

or

require('hello');

on the advice of Karma Webpack - Error: Cannot find module "./test/utilities.js"

I don't think there's anything too complicated going on here like, Cannot find module error when using karma-webpack.

I have checked to make sure that the Karma test runner is working otherwise. If I run a really simple test in its own file it works just fine.

How do I solve this problem?