Change around lib_dir handling to retain error handling

lib/benchee/system.ex

@@ -255,11 +255,13 @@ defmodule Benchee.System do
 
  # just made public for easy testing purposes
  @doc false
- def all_protocols_consolidated?(lib_dir_fun \\ &lib_dir/2) do
- case lib_dir_fun.(:elixir, :ebin) do
+ def all_protocols_consolidated?(lib_dir_fun \\ &:code.lib_dir/1) do
+ case lib_dir_fun.(:elixir) do
  # do we get a good old erlang charlist?
  path when is_list(path) ->
- [path]
+ ebin_path = Path.join(path, "ebin")
+
+ [ebin_path]
  |> Protocol.extract_protocols()
  |> Enum.all?(&Protocol.consolidated?/1)
 
@@ -271,8 +273,6 @@ defmodule Benchee.System do
  true
  end
  end
-
- defp lib_dir(app, subdir), do: Path.join(:code.lib_dir(app), subdir)
 end
 
 defimpl DeepMerge.Resolver, for: Benchee.System do

test/benchee/system_test.exs

@@ -131,7 +131,7 @@ defmodule Benchee.SystemTest do
  end
 
  test "when it borks out it warns and defaults to true, see #384" do
- fake_lib_dir = fn _, _ -> {:error, :bad_name} end
+ fake_lib_dir = fn _ -> {:error, :bad_name} end
 
  warning =
  capture_io(fn ->