Elixir ETS

ets_test.exs

defmodule SwitchWeb.ETSServiceTest do
  use ExUnit.Case

  @cache_name :switches_cache
  @value_1 "eggs"
  @value_2 "bacon"

  test "initialize cache" do
    initialize()

    assert lookup(:this_is_the_key) == {:ok, nil}
  end

  test "value lookup" do
    initialize()
    insert(:this_is_the_key, %{spam: @value_1})
    insert(:this_is_the_key, %{spam: @value_2})

    {:ok, value} = lookup(:this_is_the_key)
    assert value[:spam] == @value_2
  end

  test "access a key from a non-existent cache" do
    try do
      insert(:this_is_the_key, %{spam: @value_1})
    rescue
      e in ArgumentError -> assert e == %ArgumentError{message: "argument error"}
    end
  end

  test "deletes a key from the cache" do
    initialize()
    insert(:this_is_the_key, %{spam: @value_1})
    delete(:this_is_the_key)

    assert lookup(:this_is_the_key) == {:ok, nil}
  end

  defp initialize do
    :ets.new(@cache_name, [:set, :protected, :named_table])
  end

  defp insert(key, value) do
    :ets.insert(@cache_name, {key, value})
  end

  defp lookup(key) do
    cache_value = :ets.lookup(@cache_name, key)

    case cache_value do
      [] -> {:ok, nil}
      _ -> {:ok, cache_value[key]}
    end
  end

  defp delete(key) do
    :ets.delete(@cache_name, key)
  end
end