This example shows how to use Babel in conjunction with Mocha and Gulp.
- Clone this repository
- Navigate to this directory via
cd examples/mocha-gulp - Install the
npmdependencies vianpm install
Run npm test
When npm test is run, the aliased script in our package.json is run. That
alias is simply gulp, which runs the default gulp task.
This task is defined in gulpfile.babel.js. Let's look at that file.
You may be surprised to see that this file is exactly the same file as if we weren't using Babel. You might be wondering how that works.
The trick is that we've implicitly told Babel to transpile all of our files.
That is, in fact, the way that gulpfile.babel.js works. When you run any
gulp command within a Babel'd gulpfile, you will notice on the command line
that the first thing that is output is:
Requiring external module babel-core/register.
That's the code that transpiles everything that follows.
If we weren't using gulpfile.babel.js, we would need to manually require
in the module babel-register. Do keep that in mind if you decide not to use
ES2015 in your gulpfile.
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.
By installing the babel-core module, we're able to write ES2015 in our
Gulpfile by naming the file gulpfile.babel.js. Keep in mind that the only
reason we need babel-core is to enable this feature. If you don't wish to
use ES2015 in your Gulpfile, then you do not need to specify that dependency.
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.