missing_elixir_tests_finder.ex

defmodule Finder do
  def run do
    "find . | grep 'lib/' | grep -v 'deps/'"
    |> cmd()
    |> String.split("\n")
    |> Enum.filter(&String.ends_with?(&1, ".ex"))
    |> Enum.map(&find_test_file/1)
    |> Enum.map(&find_tests/1)
    |> Enum.filter(&has_missing_tests/1)
    |> Map.new()
  end
  
  defp find_test_file(lib_file) do
    test = lib_file
      |> String.replace("lib/", "test/")
      |> String.replace(~r/\.ex$/, "_test.exs")

    {lib_file, test}
  end
  
  defp find_tests({lib_file, test_file}) do
    dir = test_file |> Path.basename()
    cmd("mkdir #{dir}")
    cmd("touch #{test_file}")

    functions = lib_file
      |> File.read!()
      |> find_public_funcs()
      |> Enum.uniq()

    tested_functions = case File.read(test_file) do
      {:ok, test_content} -> find_describes(test_content)
      _ -> []
    end |> Enum.uniq()
    
    missing_tests = Enum.sort(functions -- tested_functions)
    
    {lib_file, missing_tests}
  end
  
  defp has_missing_tests({_lib_file, []}), do: false
  defp has_missing_tests({_lib_file, _missing_tests}), do: true
  
  defp find_public_funcs(file_content) do
    ~r/\sdef\s(\w+)/
    |> Regex.scan(file_content)
    |> Enum.map(&List.last/1)
  end
  
  defp find_describes(file_content) do    
    ~r/\sdescribe\s"(\w+)/
    |> Regex.scan(file_content)
    |> Enum.map(&List.last/1)
  end
  
  defp cmd(command) do
    command
    |> String.to_char_list
    |> :os.cmd()
    |> to_string()
    |> String.trim()
  end
end

Finder.run() |> IO.inspect(limit: :infinity)