canonical example of babel (es2015) and Mocha with source map support

index.js

export default function foo (str = 'bar') {
  if (str === 'baz') {
    throw new Error('baz is not allowed');
  }
  return str;
}

index.spec.js

import foo from '.';
import {ok} from 'assert';

describe('foo()', () => {
  it('should return "baz" (which should fail)', () => {
    ok(foo() === 'baz');
  });

  it('should print a valid stack trace', () => {
    foo('baz');
  });
});

package.json

{
  "name": "mocha-sourcemaps",
  "version": "0.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "mocha --require source-map-support --require babel-register index.spec.js"
  },
  "keywords": [],
  "author": "Christopher Hiller <[email protected]> (https://boneskull.com/)",
  "license": "ISC",
  "dependencies": {
    "babel-preset-es2015": "^6.9.0",
    "babel-register": "^6.9.0",
    "mocha": "^2.5.3",
    "source-map-support": "^0.4.0"
  },
  "babel": {
    "presets": [
      "es2015"
    ]
  }
}

Output:

$ npm test

> [email protected] test /Users/boneskull/tmp/mocha-sourcemaps
> mocha --require source-map-support --require babel-register index.spec.js



  foo()
    1) should return "baz" (which should fail)
    2) should print a valid stack trace


  0 passing (215ms)
  2 failing

  1) foo() should return "baz" (which should fail):

      AssertionError: false == true
      + expected - actual

      -false
      +true

      at Context.<anonymous> (index.spec.js:6:5)

  2) foo() should print a valid stack trace:
     Error: baz is not allowed
      at foo (index.js:3:11)
      at Context.<anonymous> (index.spec.js:10:5)

@boneskull Thanks for the example. Here is what I get when using markdown reporter with a passing test: https://gist.github.com/thomas88/6cae8efc5795bd6e60f469d9bf84b692.