Function getCompilation

test/helpers/compilation/index.js:33–160

* Gets a Webpack compiler instance to test loader operations. * @param {string} subContext * @param {Object} [options] * @param {boolean | string} [options.devtool] * @param {import('../../../loader/types').ReactRefreshLoaderOptions} [options.loaderOptions] * @param {*} [options.prevSourceMap]

(subContext, options = {})

 * @returns {Promise<CompilationSession>}
 */
async function getCompilation(subContext, options = {}) {
  const compiler = webpack({
    mode: 'development',
    cache: false,
    context: path.join(CONTEXT_PATH, subContext),
    devtool: options.devtool || false,
    entry: {
      [BUNDLE_FILENAME]: './index.js',
    },
    output: {
      filename: '[name].js',
      hashFunction: 'xxhash64',
      path: OUTPUT_PATH,
    },
    module: {
      rules: [
        {
          exclude: /node_modules/,
          test: /\.js$/,
          use: [
            {
              loader: require.resolve('@pmmmwh/react-refresh-webpack-plugin/loader'),
              options: options.loaderOptions,
            },
            !!options.devtool &&
              Object.prototype.hasOwnProperty.call(options, 'prevSourceMap') && {
                loader: path.join(__dirname, 'fixtures/source-map-loader.js'),
                options: {
                  sourceMap: options.prevSourceMap,
                },
              },
          ].filter(Boolean),
        },
      ],
    },
    plugins: [new webpack.HotModuleReplacementPlugin()],
    // Options below forces Webpack to:
    // 1. Move Webpack runtime into the runtime chunk;
    // 2. Move node_modules into the vendor chunk with a stable name.
    optimization: {
      runtimeChunk: 'single',
      splitChunks: {
        chunks: 'all',
        name: (module, chunks, cacheGroupKey) => cacheGroupKey,
      },
    },
  });

  // Use an in-memory file system to prevent emitting files
  compiler.outputFileSystem = createFsFromVolume(new Volume());

  /** @type {import('memfs').IFs} */
  const compilerOutputFs = compiler.outputFileSystem;
  /** @type {import('webpack').Stats | undefined} */
  let compilationStats;

  await new Promise((resolve, reject) => {
    compiler.run((error, stats) => {