coveralls elixir setup

coveralls_mix.exs

defmodule Chat.Mixfile do
  defp deps do
    [{:excoveralls, only: :test}]
  end

  defp test(args) do
    ...
    Mix.Task.run("test")

    Mix.shell.info("")
    Mix.shell.info("$ mix coveralls                 - coverage overview")
    Mix.shell.info("$ mix coveralls.detail FILENAME - line-by-line coverage of file")
  end

  defp cli_env do
    [coveralls: :test,
     "coveralls.detail": :test]
  end
end