A rule which states that all modules must have documentation in the form of a @moduledoc attribute.

This rule does run check interpreted Elixir files, i.e. those with the file extension .exs.

This would be valid according to this rule:

defmodule MyModule do
  @moduledoc """
  This module is valid as it has a moduledoc!
  Ideally the documentation would be more useful though...
  """
end

This would not be valid:

defmodule MyModule do
end

If you do not want to document a module, explicitly do so by setting the attribute to false.

defmodule MyModule do
  @moduledoc false
end