Enable istanbul coverage on ES2015/babel or coffee-script/cjsx files when you do mocha/jasmine tests, also deal with sourceMap for coverage report and stack trace.

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Enable istanbul coverage on ES2015/babel files when you do mocha/jasmine tests, also deal with sourceMap for stack gulp task.
npm version npm download Dependency Status Build Status License
  • Help you create a gulp task to handle mocha testing + istanbul coverage
  • Transpile .jsx and ES2015 .js files on the fly
  • Use babel to transpile .js and .jsx files so you can use ES2015 features inside your .js and .jsx files!
  • Customize everything by options
  • sourceMaps on stack traces when mocha test failed (powered by source-map-support)
  • coverage threshold

ORIGINAL CODE/LINE in coverage reports
ORIGINAL CODE/LINE in stack traces
  1. Install
---------- For Mocha tests:
npm install gulp gulp-jsx-coverage gulp-mocha babel-plugin-istanbul --save-dev

For Jasmine tests:
npm install gulp gulp-jsx-coverage gulp-jasmine babel-plugin-istanbul --save-dev

  1. Configure Babel

Configure your .babelrc and install proper presets or plugins.
Here is a .babelrc example:
  presets: ['es2015', 'react']
And then:
npm install babel-preset-es2015 babel-preset-react

  1. Create Gulp Task

Put this into your gulpfile.js:
gulp.task('your_task_name', require('gulp-jsx-coverage').createTask({
    src: ['test/**/*.js', 'test/components/*.jsx'],  // your test files

Then run the task: gulp your_task_name
Best Practices
  • The golden rule: Use .jsx as ext name when jsx syntax inside it. Require it by require('file.jsx').
  • When you develop a module, do not use any module loader hooks. (Refer to Babel require hook document)
  • Excludes babel as possible as you can to improve babel performance.
  • When you develop an application, you may use module loader hooks. But, don't enable the hook when you do testing.
Usage: General Mocha Test Creator
gulp.task('your_task_name', require('gulp-jsx-coverage').createTask({
    src: ['test/**/*.js', 'test/components/*.jsx'],  // will pass to gulp.src as mocha tests

    istanbul: {                                      // will pass to istanbul, this is default setting
        exclude: /node_modules|test[0-9]/            // do not instrument these files

    threshold: [                                     // fail the task when coverage lower than one of this array
            type: 'lines',                           // one of 'lines', 'statements', 'functions', 'banches'
            min: 90

    babel: {                                         // this is default setting
        include: /\.jsx?$/,
        exclude: /node_modules/,
        omitExt: false                               // if you wanna omit file ext when require(), put an array
    },                                               // of file exts here. Ex: ['.jsx', '.es6'] (NOT RECOMMENDED)

    coverage: {
        reporters: ['text-summary', 'json', 'lcov'], // list of istanbul reporters
        directory: 'coverage'                        // will pass to istanbul reporters

    mocha: {                                         // will pass to mocha
        reporter: 'spec'

    cleanup: function () {
        // do extra tasks after test done
        // EX: clean global.window when test with jsdom
Usage: Other Testing Frameworks
var GJC = require('gulp-jsx-coverage');
var jasmine = require('gulp-jasmine');

gulp.task('my_jasmine_tests', function () {
    GJC.initModuleLoader(GJCoptions);                     // Refer to previous gulp-jsx-coverage options

    return gulp.src('test/*.js')
    .on('end', GJC.collectIstanbulCoverage(GJCoptions));  // Refer to previous gulp-jsx-coverage options
Live Example: mocha
git clone
cd gulp-jsx-coverage
npm install
npm run mocha

~/gulp-jsx-coverage master>npm run mocha

> gulp-jsx-coverage@0.3.8 mocha /Users/zordius/gulp-jsx-coverage
> gulp mocha_tests

[11:50:14] Using gulpfile ~/gulp-jsx-coverage/gulpfile.js
[11:50:14] Starting 'mocha_tests'...

 target (tested by test1.js)
   ✓ should multiply correctly
   - should not show coverage info for test1.js
   ✓ should handle es2015 template string correctly

 target (tested by test2.jsx)
   ✓ should multiply correctly (77ms)
   - should not show coverage info for test2.jsx
   1) should exception and failed

 Component.jsx (tested by test2.jsx)
   ✓ should render Hello World

 4 passing (104ms)
 2 pending
 1 failing

 1) target (tested by test2.jsx) should exception and failed:
    TypeError: "hohoho
this is
multi line
error!".notAFunction is not a function
     at Context.<anonymous> (test2.jsx:34:10)

[11:50:16] 'mocha_tests' errored after 1.86 s
[11:50:16] Error in plugin 'gulp-mocha'
   1 test failed.
File           |  % Stmts | % Branch |  % Funcs |  % Lines |Uncovered Lines |
All files      |    90.48 |      100 |       75 |    90.48 |                |
Component.jsx |       75 |      100 |       50 |       75 |              5 |
target.js     |       80 |      100 |    66.67 |       80 |              8 |
testlib.js    |      100 |      100 |      100 |      100 |                |

Upgrade Notice
  • Core changed:
do not support isparta now do not support coffee-script/cjsx now do not support options.babel now (please use .babelrc) do not support now move to istanbul.js and babel-plugin-istanbul now
  • API changed:
you should rename all colloectIstanbulCoverage into collectIstanbulCoverage
  • Babel upgraded:
You should add proper options.babel.plugins or options.babel.presets to transpile your script properly. Please refer to
  • API changed:
you should rename all initIstanbulHookHack into initModuleLoaderHack
  • the sourceMap stack trace feature requires:
mocha >= 2.2.2 the options.babel.sourceMap should be changed from 'inline' to 'both'