And-ing and Or-ing list elements

list_truther.exs

defmodule ListTruther do

  def test([],_) do
    false
  end

  def test(list, mode) do
    case mode do
      :and -> Enum.reduce_while(list, false, fn(item, _) ->
        if item, do: {:cont, true}, else: {:halt, false}
      end)
      :or -> Enum.reduce_while(list, false, fn(item, _) ->
        unless item, do: {:cont, false}, else: {:halt, true}
      end)
    end
  end
end

ExUnit.start

defmodule ListTrutherTest do
  use ExUnit.Case, async: true

  test "list_and empty list is false" do
    assert false == ListTruther.test([], :and)
  end

  test "list_and; all false" do
    assert false == ListTruther.test([false, false, false], :and)
  end

  test "list_and; all true" do
    assert true == ListTruther.test([true, true, true], :and)
  end

  test "list_and; not all false" do
    assert false == ListTruther.test([true, false, true], :and)
  end

  test "list_or; empty list is false" do
    assert false == ListTruther.test([], :or)
  end

  test "list_or; all false" do
    assert false == ListTruther.test([false, false, false], :or)
  end

  test "list_or; all true" do
    assert true == ListTruther.test([true, true, true], :or)
  end

  test "list_or; not all true" do
    assert true == ListTruther.test([true, false, true], :or)
  end
end