mocha-cli

Mocha + CLI

This example shows how to use Babel in conjunction with Mocha. It doesn't use any task runner, like Grunt or Gulp; it's CLI-based.

Installation

1. Clone this repository
2. Navigate to this directory via cd examples/mocha-cli
3. Install the npm dependencies via npm install

Running the tests

Run npm test

How it works

When npm test is run, the aliased script in our package.json is run. We can see in package.json that the associated command is: mocha unit/*.js --compilers js:babel-register.

Let's break down that command piece-by-piece:

mocha

This is just running the Mocha CLI. It doesn't need to be installed globally because we've specified mocha as a devDependency for our package.

unit/*.js

These are where the unit tests are located.

--compilers js:babel-register

This is an option exposed by Mocha's CLI. The value we've passed indicates that for all files ending in js, we wish to use the babel-register library to compile our code before running the tests.

The babel-register library is a tool that transpiles anything that we require in. Because mocha is a Node tool, it ultimately requires in each of our unit tests. This is what allows us to write our tests in ES2015 as well as our library itself.

.babelrc

There's one last important detail that makes all of this work: the .babelrc file. Our configuration in that file tells Babel that we want to transpile ES2015 code into ES5 code. This is necessary because Babel makes no assumptions about how you want to transform the code as of v6.

A note on Chai

These examples all use Chai as the assertion library for the tests. It should be relatively straightforward to swap it out for your assertion library of choice, which is why I haven't included other examples. If you're having trouble, raise an issue and I'll be glad to help out.