Adds module to parse arguments passed to mediate

lib/options.ex

@@ -0,0 +1,16 @@
+defmodule Options do
+
+  def parse([]), do: defaults
+  def parse(args) do
+    Enum.reduce(args, defaults, fn(arg, acc) ->
+      Map.merge(acc, parse_argument(arg))
+    end)
+  end
+
+  def parse_argument("--clear-screen"), do: %{ clear_screen: true}
+  def parse_argument(_), do: %{}
+
+  defp defaults do
+    %{ clear_screen: false}
+  end
+end

test/options_test.exs

@@ -0,0 +1,18 @@
+defmodule OptionTest do
+  use ExUnit.Case, async: true
+
+  test "has default options" do
+    options = Options.parse([])
+    refute Map.fetch!(options, :clear_screen)
+  end
+
+  test "override clearing of screen" do
+    options = Options.parse(["--clear-screen"])
+    assert Map.fetch!(options, :clear_screen)
+  end
+
+  test "ignores unknown options" do
+    options = Options.parse(["--foo"])
+    refute Map.fetch!(options, :clear_screen)
+  end
+end