Sample Phoenix + Brunch (Babel) + Mocha test setup for unit tests

.babelrc

{
  "presets": ["es2015"]
}

0_readme.md

No changes to brunch-config.js (if you're already using Babel, which I think is the default)

The directory I put all my JS unit tests are in test/js (you can set this path on line 18 of package.json)

I wasn't able to put files in subdirectories in this gist, so the files that belong in other directories are clearly marked so in a comment on the first line.

package.json

{
  "repository": {},
  "dependencies": {
    "babel-brunch": "^6.0.0",
    "babel-core": "^6.0.0",
    "brunch": "^2.1.1",
    "javascript-brunch": ">= 1.0 < 1.8",
    "phoenix": "file:deps/phoenix",
    "phoenix_html": "file:deps/phoenix_html",
    "uglify-js-brunch": ">= 1.0 < 1.8"
  },
  "devDependencies": {
    "babel-preset-es2015": "^6.5.0",
    "babel-register": "^6.5.1",
    "mocha": "^2.4.5"
  },
  "scripts": {
    "test": "mocha --compilers js:babel-register test/js/**/*.js"
  }
}

something.js

// This file lives in `web/static/js/something.js`

export default function() {
  return "something";
}

something_test.js

// This file lives in `test/js/something_test.js`

import assert from 'assert';
import something from '../../web/static/js/something'

describe('something()', function() {
  it('does something', function () {
    assert.equal("something", something());
  });
});

It works like charm. The missing part for me was needlessly pointing to the root of js static files instead of test directory itself. Again, thank you @keichan34 !