Add Elixir files to your compiled list

While working on an Elixir package today, I wanted to add the test/support directory to my compiled files. I knew the Phoenix Framework did this so I went there to take a look and discovered elixirc_paths.

The Phoenix frameworks example looks like this:

  # mix.exs
  def project do
    [
      ...
      elixirc_paths: elixirc_paths(Mix.env),
      ...
    ]
  end
  defp elixirc_paths(:test), do: ["lib", "test/support"]
  defp elixirc_paths(_),     do: ["lib"]

Perfect! Now we can add additional directories to our compiled path that are environment specific.