finalize = (err, src) => {
    if (err) {
      callback(err);
      return;
    }
    if (!loader.specsForComponents) {
      callback(err, src);
      return;
    }
    if (!loader.specsForComponents[componentName]) {
      callback(err, src);
      return;
    }
    const specPath = loader.specsForComponents[componentName];
    fs.readFile(path.resolve(loader.baseDir, specPath), 'utf-8', (fsErr, specs) => {
      if (fsErr) {
        // Ignore spec reading errors
        callback(err, src);
        return;
      }
      callback(err, {
        ...src,
        tests: specs,
      });
    });
  }
@param {Error|null} err
@param {Object} [src]