EDIT: I came up with a even better way to debug Elixir code than using iex, check it here.

Interactive Driven Development, or REPL Driven Development is a really good way to approach programming, specially for developers that get distracted easily with time being expend out the main development loop or flow.

A way to do it in Elixir is just to use the fswatch as presented in Elixir Mix Test documentation, or using the excellent mix.test-watch library, but them don't work well with iex, the Elixir REPL, so why not do something else.

So I created some modules that can be imported on your iex through the ~/.iex.exs file and get the same benefits.

Just insert it on your ~/.iex.exs file:

And create a ~/.iex directory, placing this file on it:

There is an explanition about how to use it on the @moduledoc, but briefly you just need to call iex prepending the ~/.iex directory on the Elixir path:

  ELIXIR_ERL_OPTIONS="-pa $HOME/.iex" MIX_ENV=test iex -S mix

The IExWatchTests.Helpers that is imported on ~/.iex.exs allows to call f and s and a to run failed, stale and all tests respectively.

You can call w to watch tests and uw to unwatch.

There is a really simple throttle mechanism that disallow run the suite concurrently.

That is all. Enjoy!