compilers deprecation

If you're here, you probably hit the deprecation notice. Sorry about that!

Will it break?

This is a soft deprecation, which means you get nagged about it, but it won't break (yet).

Make it go away

To suppress this warning, execute mocha with the --no-deprecation flag (though you won't get notice of any other deprecations you may encounter either).

... but why?

--compilers is redundant; we've yet to encounter a real-world situation in which the solution couldn't be expressed using --require.

What should I use instead then?

For example, --compilers coffee:coffee-script/register can be expressed as --require coffee-script/register. Likewise, --compilers js:babel-register can be expressed as --require babel-register.

However, Mocha loads only .js files by default when running all files in a directory. Therefore, to use a different file extension (such as .coffee), you will need to supply a glob instead of simply a directory. If this was how you ran Mocha pre-v4:

$ mocha --compilers coffee:coffee-script/register --recursive ./test

Then this is how you'd accomplish the same thing (** roughly means "recursive") in v4:

$ mocha --register coffee-script/register "test/**/*.js"

When you wrap a glob in quotes, file discovery is handed to the glob package. It's recommended to wrap in double-quotes, because the result should be the same regardless of your shell or environment (Windows/Linux/macOS, etc.).

glob is powerful. For instance, if your test dir has tests written in both JS and CoffeeScript, you could do this:

$ mocha --register coffee-script/register "test/**/*.{js,coffee}"

How do I use this with --watch?

When using --watch, you will also need to specify the extension(s) to watch via --watch-extensions, e.g.:

$ mocha --register coffee-script/register --watch --watch-extensions js,coffee "test/**/*.{js,coffee}"

This isn't working

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