如何用#webpack来衡量我所有源代码的覆盖率？

npm install webpack webpack-cli babel-loader @babel/core @babel/preset-env istanbul-instrumenter-loader karma karma-webpack karma-coverage-istanbul-reporter karma-chrome-launcher --save-dev

const path = require('path');

module.exports = {
  entry: './src/index.js',
  output: {
    filename: 'bundle.js',
    path: path.resolve(__dirname, 'dist'),
  },
  module: {
    rules: [
      {
        test: /\.js$/,
        exclude: /node_modules/,
        use: {
          loader: 'babel-loader',
          options: {
            presets: ['@babel/preset-env'],
          },
        },
      },
      {
        test: /\.js$/,
        exclude: /node_modules/,
        enforce: 'post',
        use: {
          loader: 'istanbul-instrumenter-loader',
          options: { esModules: true },
        },
      },
    ],
  },
};

module.exports = function (config) {
  config.set({
    frameworks: ['jasmine'],
    files: ['src/**/*.spec.js'],
    preprocessors: {
      'src/**/*.spec.js': ['webpack'],
    },
    webpack: {
      module: {
        rules: [
          {
            test: /\.js$/,
            exclude: /node_modules/,
            use: {
              loader: 'babel-loader',
              options: {
                presets: ['@babel/preset-env'],
              },
            },
          },
        ],
      },
    },
    reporters: ['progress', 'coverage-istanbul'],
    coverageIstanbulReporter: {
      reports: ['html', 'lcovonly', 'text-summary'],
      dir: path.join(__dirname, 'coverage'),
      fixWebpackSourcePaths: true,
    },
    browsers: ['Chrome'],
    singleRun: true,
  });
};

"scripts": {
  "test": "karma start"
}

import { sum } from './index';

describe('sum', () => {
  it('should return the sum of two numbers', () => {
    expect(sum(1, 2)).toBe(3);
  });
});

npm test