mix-failed

#!/usr/bin/env elixir
for path <- Path.wildcard("_build/test/lib/*/.mix/.mix_test_failures", match_dot: true),
    {{mod, name}, path} <-
      path
      |> File.read!()
      |> :erlang.binary_to_term()
      |> elem(1)
      |> Map.to_list(),
    grep_match <-
      name
      |> to_string()
      |> String.split()
      |> Stream.unfold(fn
        [] ->
          nil

        [_ | words] ->
          search_term = Enum.join(words, " ")

          System.cmd("rg", ["-w", search_term, "--vimgrep", path])
          |> case do
            {"", 1} -> {nil, words}
            {matches, 0} -> {matches, []}
          end
      end)
      |> Stream.reject(&is_nil/1)
      |> Enum.to_list(),
    into: IO.stream(:stdio, :line) do
  [path, line, col, _] = String.split(grep_match, ":", parts: 4)
  "#{Path.relative_to_cwd(path)}:#{line}:#{col}: #{mod} #{name}\n"
end

Example output