Plug unit testing

router.ex

defmodule LearningElixir.Router do
  use Plug.Router

  if Mix.env == :dev do
    use Plug.Debugger
  end

  plug :match
  plug :dispatch

  # root path
  get "/" do
    send_resp(conn, 200, "Hello")
  end
  
  match _ do
    send_resp(conn, 404, "oops")
  end
end

router_text.exs

defmodule LearningElixir.Router do
  use ExUnit.Case, async: true
  use Plug.Test

  alias LearningElixir.Router

  @opts Router.init([])

  test "returns hello text" do
    response = conn(:get, "/")
               |> Router.call([])

    assert response.status == 200
  end
end