node.js - Running Mocha + Istanbul + Babel

Question

I'm having some issues while running Istanbul with Mocha and the Babel compiler.

All my tests are running just fine, but after all the tests done it shows me this message:

No coverage information was collected, exit without writing coverage information

And it is not producing any coverage report.

The command that I am running is:

NODE_ENV=test istanbul cover _mocha -- --require babel-core/register --recursive

The project is hosted on GitHub: https://github.com/weslleyaraujo/react-flux-puzzle/tree/feat/unit-tests-24

Any ideas what it could be?

Answer 1

Using Babel 6.x, let's say we have file test/pad.spec.js:

import pad from '../src/assets/js/helpers/pad';
import assert from 'assert';

describe('pad', () => {
  it('should pad a string', () => {
    assert.equal(pad('foo', 4), '0foo');
  });
});

Install a bunch of crap:

$ npm install babel-istanbul babel-cli babel-preset-es2015 mocha

Create a .babelrc:

{
  "presets": ["es2015"]
}

Run the tests:

$ node_modules/.bin/babel-node node_modules/.bin/babel-istanbul cover    
node_modules/.bin/_mocha -- test/pad.spec.js


  pad
    ? should pad a string


  1 passing (8ms)

=============================================================================
Writing coverage object [/Volumes/alien/projects/forked/react-flux-puzzle/coverage/coverage.json]
Writing coverage reports at [/Volumes/alien/projects/forked/react-flux-puzzle/coverage]
=============================================================================

=============================== Coverage summary ===============================
Statements   : 100% ( 4/4 )
Branches     : 66.67% ( 4/6 ), 1 ignored
Functions    : 100% ( 1/1 )
Lines        : 100% ( 3/3 )
================================================================================

UPDATE: I've had success using nyc (which consumes istanbul) instead of istanbul/babel-istanbul. This is somewhat less complicated. To try it:

Install stuff (you can remove babel-istanbul and babel-cli):

$ npm install babel-core babel-preset-es2015 mocha nyc

Create .babelrc as above.

Execute this:

$ node_modules/.bin/nyc --require babel-core/register node_modules/.bin/mocha  
test/pad.spec.js

...which should give you similar results. By default, it puts coverage info into .nyc-output/, and prints a nice text summary in the console.

Note: You can remove node_modules/.bin/ from any of these commands when placing the command in package.json's scripts field.