Unexpected token ILLEGAL on @import Testing React/ES6 with Mocha

Question

Looks related to Babel unexpected token import when running mocha tests and may be a duplicate but, having tried those solutions, I am still facing issues.

Trying to use Mocha to run some tests:

./node_modules/.bin/mocha --compilers js:babel-core/register

Issue

$ ./node_modules/.bin/mocha --compilers js:babel-core/register C:\devel\jtreports\node_modules\react-widgets\lib\less\react-widgets.less:1 (function (exports, require, module, __filename, __dirname) { @import "./variables.less"; ^

SyntaxError: Unexpected token ILLEGAL at exports.runInThisContext (vm.js:53:16)

First not sure why the import(must have something misconfigured) is an issue and second, the node_modules is being processed? Expecting the node_modules directory to be excluded as per the webpack configuration below.

webpack.config.js:

const webpack = require('webpack');

module.exports = {
    entry: [
        'webpack-dev-server/client?http://localhost:80',
        './app/main.js'
    ],
    output: {
        path: './app',
        filename: 'app.bundle.js'
    },
    module: {
        loaders: [
            {
                test: /\.js?$/,
                exclude: /node_modules/,
                loaders: ["babel-loader"]
            },
            {
                test: /\.css$/,
                loader: "style-loader!css-loader"
            },
            {
                test: /\.less$/,
                loader: "style-loader!css-loader!less-loader"
            },
            {
                test: /\.woff(2)?(\?v=[0-9].[0-9].[0-9])?$/,
                loader: "url-loader?mimetype=application/font-woff"
            },
            {
                test: /\.(ttf|eot|svg)(\?v=[0-9].[0-9].[0-9])?$/,
                loader: "file-loader?name=[name].[ext]"
            },
            {
                test: /\.(jpe?g|png|gif|svg)$/i,
                loaders: [
                    'file?hash=sha512&digest=hex&name=[hash].[ext]',
                    'image-webpack?bypassOnDebug&optimizationLevel=7&interlaced=false'
                ]
            }
        ]
    },
    resolve: {
        extensions: ['', '.js', '.jsx']
    },
    devServer: {
        hot: true,
        inline: true,
        host: 'localhost',
        port: 80,
        contentBase: "./app",
        secure: false,
        colors: true,
        noInfo: false,
        proxy: {
            '/rest': {
                target: 'http://localhost:8080',
            }
        },
        historyApiFallback: true
    },
    plugins: [
        new webpack.HotModuleReplacementPlugin()
    ]
}

.bablerc

{
  "presets": [
    "es2015",
    "react"
  ],
  "plugins": [
    [
      "transform-object-rest-spread",
      "transform-react-jsx-img-import",
      "react-transform",
      {
        "transforms": [
          {
            "transform": "react-transform-hmr",
            "imports": [
              "react"
            ],
            "locals": [
              "module"
            ]
          }
        ]
      }
    ]
  ]
}