propcheck_config.ex

defmodule PropCheckConfig do
  def config() do
    [:quiet]
    |> push("NUMTESTS", "30", :numtests, &opt_num_value/2)
    |> maybe_push("VERBOSE", :verbose)
    |> maybe_push("MAX_SIZE", :max_size, &opt_num_value/2)
  end

  defp opt_num_value(name, val), do: {name, String.to_integer(val)}

  defp push(cfg, env_var, default , opt_name, transform \\ fn opt, _val -> opt end) do
    case System.get_env(env_var) do
      nil -> [transform.(opt_name, default) | cfg]
      val -> [transform.(opt_name, val) | cfg]
    end
  end

  defp maybe_push(cfg, env_var, opt_name, transform \\ fn opt, _val -> opt end) do
    case System.get_env(env_var) do
      nil -> cfg
      val -> [transform.(opt_name, val) | cfg]
    end
  end
end