find_deep_value.exs

defmodule EnumTools do
  def find_deep_value(map, value) when is_map(map) do
    map |> Map.values |> Enum.any?(
      fn
        val when is_map(val) -> find_deep_value(val, value)
        val when val == value -> true
        _ -> false
      end)
  end
end


# run this inline suite with "elixir #{__ENV__.file} test"
if System.argv |> List.first == "test" do
  ExUnit.start

  defmodule FindDeepTest do
    use ExUnit.Case, async: true
    alias EnumTools, as: ET

    test "find a deep value" do
      assert ET.find_deep_value(%{a: %{b: %{c: "d"}, e: "f"}, g: "h"}, "d")
    end

    # negative case
    test "could not find a deep value" do
      refute ET.find_deep_value(%{a: %{b: %{c: "d"}}}, "f")
    end

  end
end