Learn Me Some Plug

learning_plug.ex

defmodule LearningPlug do
  use Plug.Builder

  plug Plug.Logger
  plug :extract_name
  plug :greet, %{my_option: "Hello"}

  def extract_name(%Plug.Conn{request_path: "/" <> name} = conn, opts) do
    assign(conn, :name, the_name(name))
  end

  def greet(conn, opts) do
    conn
    |> send_resp(200, "#{opts[:my_option]}, #{conn.assigns.name}")
  end

  defp the_name(name) do
    if (String.length(name) == 0), do: "foobar", else: name
  end
end

learning_plug_test.exs

defmodule LearningPlugTest do
  use ExUnit.Case
  use Plug.Test
  doctest LearningPlug

  test "responds with 'Hello, foobar' for no name provided" do
    conn = conn(:get, "/", "")
           |> LearningPlug.call(%{})
    
    assert conn.state == :sent
    assert conn.status == 200
    assert conn.resp_body == "Hello, foobar"
  end

  test "responds with 'Hello, todd' for name todd provided" do
    conn = conn(:get, "/todd", "")
           |> LearningPlug.call(%{})

    assert conn.state == :sent
    assert conn.status == 200
    assert conn.resp_body == "Hello, todd"
  end
end