Getting "Invariant Violation: webpackConfig must be a plain object"

[codeuniquely]

I have basically tried to set up my project in line with configuration in the thread #19

But I'm getting this error when I try to run mocha-webpack

File [/Users/steve/project/webpack.test.config.js] ignored, nothing could be mapped
/Users/steve/project/node_modules/invariant/invariant.js:49
    throw error;
    ^

Invariant Violation: webpackConfig must be a plain object
    at invariant (/Users/steve/project/node_modules/invariant/invariant.js:42:15)
    at createCompiler (/Users/steve/Project/node_modules/mocha-webpack/lib/webpack/createCompiler.js:32:27)
    at build (/Users/steve/project/node_modules/mocha-webpack/lib/webpack/build.js:19:47)
    at run (/Users/steve/projects/node_modules/mocha-webpack/lib/cli/runner.js:49:23)
    at /Users/steve/project/node_modules/mocha-webpack/lib/cli/index.js:59:21
    at /Users/steve/project/node_modules/mocha-webpack/lib/cli/prepareWebpack.js:188:11
    at _combinedTickCallback (internal/process/next_tick.js:67:7)
    at process._tickCallback (internal/process/next_tick.js:98:9)
    at Function.Module.runMain (module.js:577:11)
    at Function.runMain (/Users/steve/.node-spawn-wrap-5982-492946983996/node:40:10)
    at Object.<anonymous> (/Users/steve/project/node_modules/nyc/bin/wrap.js:22:4)
    at Module._compile (module.js:541:32)
    at Object.Module._extensions..js (module.js:550:10)
    at Module.load (module.js:458:32)
    at tryModuleLoad (module.js:417:12)
    at Function.Module._load (module.js:409:3)
    at Function.Module.runMain (module.js:575:10)
    at Object.<anonymous> (/Users/steve/.node-spawn-wrap-5982-492946983996/node:140:8)
    at Module._compile (module.js:541:32)
    at Object.Module._extensions..js (module.js:550:10)
    at Module.load (module.js:458:32)
    at tryModuleLoad (module.js:417:12)
    at Function.Module._load (module.js:409:3)
    at Module.runMain (module.js:575:10)
    at run (bootstrap_node.js:352:7)
    at startup (bootstrap_node.js:144:9)
    at bootstrap_node.js:467:3

in webpack.config.test.js

var webpack         = require('webpack');
var path            = require('path');
var nodeExternals   = require('webpack-node-externals');

// Define the environment
var env             = 'test';

// ==============================
//  Paths
// ==============================
var rootPath        = path.resolve( __dirname );
var nodeModulesPath = path.resolve( __dirname, 'node_modules');
var buildPath       = path.resolve( __dirname, 'build');
var srcPath         = path.resolve( __dirname, 'src' );
var serverPath      = path.resolve( srcPath, 'server' );
var libPath         = path.resolve( srcPath, 'lib' );
var modelPath       = path.resolve( srcPath, 'models' );
var routePath       = path.resolve( srcPath, 'routes' );

// ==============================
//  CommonJS wrap all Externals
// ==============================
var extNodeModules  = nodeExternals();

// ==============================
//  Plugins
// ==============================
var plugins = [

  new webpack.DefinePlugin({
    'process.env': {
      ENV: JSON.stringify(env),
      NODE_ENV: JSON.stringify(env)
    }
  }),

  new webpack.NoErrorsPlugin()
];

// ==============================
//  Pre-loaders
// ==============================
var preLoaders = [
  {
    test: /\.js$/i,
    loaders: ['babel'],
    exclude: [
      nodeModulesPath       // skip anything in node_modules
    ]
  },
  {
    test: /\.js$/i,
    include: srcPath,
    exclude: [
      nodeModulesPath,      // skip anything in node_modules
      /\.spec\.js$/         // skip instrumentaion on *.spec.js files
    ],
    loader: 'istanbul-instrumenter'
  }
];

// ==============================
//  Loaders
// ==============================
var loaders = [
  { test: /\.json$/i, loader: 'json' }
];

module.exports = {
  resolve: {
    alias:{
      root: rootPath,
      server: serverPath,
      src: srcPath,
      lib: libPath,
      models: modelPath,
      routes: routePath,
      node: nodeModulesPath
    },
    extensions: ['', '.js', '.json' ]
  },
  target: 'node',
  externals: [ extNodeModules ],
  plugins: plugins,
  module: {
    preLoaders: preLoaders,
    loaders: loaders
  }
};

in package.json

  "scripts": {
     "test": "NODE_ENV=test BABEL_ENV=test nyc mocha-webpack",
  },
  "nyc": {
    "reporter": [
      "lcov",
      "text-summary"
    ],
    "exclude": [
      "node_modules",
      "test"
    ]
  },
  "devDependencies": {
    "babel-core": "^6.13.2",
    "babel-loader": "^6.2.5",
    "babel-plugin-istanbul": "^2.0.1",
    "babel-preset-es2015": "^6.13.2",
    "babel-preset-stage-0": "^6.5.0",
    "istanbul-instrumenter-loader": "^1.0.0",
    "json-loader": "^0.5.3",
    "mocha": "^3.0.2",
    "mocha-webpack": "^0.7.0",
    "nyc": "^8.3.1",
    "webpack": "^1.13.2"
  }

in mocha.options.json

--require babel-core/register
--colors
--reporter spec
--ui bdd
--webpack-config webpack.test.config.js
src/**/*.spec.js

in babel.rc

{
  "presets": ["es2015", "stage-0"],
  "env": {
    "test": {
      "plugins": ["istanbul"]
    }
  }
}

[codeuniquely]

after a bit of debugging

createCompiler.js

function createCompiler(webpackConfig) {
 (0, _invariant2.default)(_lodash2.default.isPlainObject(webpackConfig), 'webpackConfig must be a plain object');
}

which makes a call into lodash.isPlainObject()

function isPlainObject(value) {
  if (!isObjectLike(value) || objectToString.call(value) != objectTag) {
    return false;
  }
  var proto = getPrototype(value);
  if (proto === null) {
    return true;
  }
  var Ctor = hasOwnProperty.call(proto, 'constructor') && proto.constructor;
  return (typeof Ctor == 'function' &&
    Ctor instanceof Ctor && funcToString.call(Ctor) == objectCtorString);
}

when I look at the variables
objectToString.call(value) => "[object Array]"

whereas objectTag is expecting "[object Object]"

the contents of value are

Array[1]
  context:"/Users/steve/Projects/CallMeBack/procheck-api/.tmp/mocha-webpack"
  entry:"./1a060d55bfc9cb75db0c27c8d4597b28-entry.js"

  output:Object
  plugins:Array[2]
    [0]:WebpackInfoPlugin
    [1]:ContextReplacementPlugin
  Object[0]
    babel:Object
    externals:Array[1]
      [0]:function (context, request, callback) { … }
    module:Object
      loaders:Array[3]
      preLoaders:Array[2]
    plugins:Array[2]
      [0]:DefinePlugin
      [1]:NoErrorsPlugin
    resolve:Object
      alias:Object
      extensions:Array[3]
        [0]:""
        [1]:".js"
        [2]:".json"
    target:"node"

Not really sure what to do here as I simply just pass a reference to the webpack config file and its the same format that I use for development / build and deployment

[codeuniquely]

Worked it out:
I was bundling several parts UI, Proxy, BackEnd into an array and passing that back to webpack (more than one server is being build)

for testing I just pass each in turn builds[0] ... builds[3]