replace 'onBrowserComplete' on karma-coverage with 

  this.onBrowserComplete = function(browser, result) {
    var collector = collectors[browser.id];
    var results;
    var replacedBasePath;
    var replacedKey;
    var keyAux;
    var keys;
    var keysIndex;
    
    if (!collector) {
      return;
    }

    if (result && result.coverage) {

      if (rootConfig.jsxBuild) {
        keys = Object.keys(result.coverage);
        replacedBasePath = rootConfig.basePath;
        results = {};

        while (replacedBasePath.indexOf('/') !== -1) {
          replacedBasePath = replacedBasePath.replace('/', '\\');
        }

        for (keysIndex = 0; keysIndex < keys.length; keysIndex++) {
          keyAux = keys[keysIndex];

          if (keyAux.indexOf(replacedBasePath) === -1) {
            replacedKey = keyAux.replace('.', replacedBasePath)
            while (replacedKey.indexOf('/') !== -1) {
              replacedKey = replacedKey.replace('/', '\\');
            }

            results[replacedKey] = result.coverage[replacedKey];
            results[replacedKey].path = keyAux;
          }
        }
      } else {
        results = result.coverage;
      }

      collector.add(results);
    }
  };