Support the /who chat command

lib/ex_chat/use_cases/who_am_i.ex

@@ -0,0 +1,6 @@
+defmodule ExChat.UseCases.WhoAmI do
+
+  def on(session_id) do
+    {:ok, "You are logged in as #{session_id}"}
+  end
+end

lib/ex_chat/web/websocket_controller.ex

@@ -4,7 +4,7 @@ defmodule ExChat.Web.WebSocketController do
   end
 
   alias ExChat.UseCases.{ValidateAccessToken, SendMessageToChatRoom,
-    CreateChatRoom, JoinChatRoom, SubscribeToUserSession}
+    CreateChatRoom, JoinChatRoom, SubscribeToUserSession, WhoAmI}
 
   @default_ping_interval 30_000
   @default_idle_timeout 60_000
@@ -60,6 +60,11 @@ defmodule ExChat.Web.WebSocketController do
     handle(Map.put(command, "room", "default"), session_id)
   end
 
+  defp handle(%{"message" => "/who"}, session_id) do
+    {:ok, message} = WhoAmI.on(session_id)
+    {:reply, {:text, to_json(%{message: message})}, session_id}
+  end
+
   defp handle(%{"room" => room, "message" => message}, session_id) do
     case SendMessageToChatRoom.on(message, room, session_id) do
       {:error, message} ->

test/ex_chat/use_cases/who_am_i_test.exs

@@ -0,0 +1,9 @@
+defmodule ExChat.UseCases.WhoAmITest do
+  use ExUnit.Case, async: true
+
+  alias ExChat.UseCases.WhoAmI
+
+  test "return a message telling the user how they are logged in" do
+    assert WhoAmI.on("a-user") == {:ok, "You are logged in as a-user"}
+  end
+end

test/ex_chat/web/websocket_acceptance_test.exs

@@ -84,6 +84,25 @@ defmodule ExChat.Web.WebSocketAcceptanceTest do
     end
   end
 
+  describe "As a User when I send the /who command" do
+    setup :connect_as_a_user
+
+    test "I receive back my logged in information", %{client: client} do
+      send_as_text(client, "{\"room\":\"default\",\"message\":\"/who\"}")
+
+      assert_receive "{\"message\":\"You are logged in as a-user\"}"
+    end
+
+    test "a message that merely contains /who is broadcast as usual", %{client: client} do
+      send_as_text(client, "{\"command\":\"join\"}")
+
+      send_as_text(client, "{\"room\":\"default\",\"message\":\"who is there /who\"}")
+
+      assert_receive "{\"room\":\"default\",\"from\":\"a-user\",\"message\":\"who is there /who\"}"
+      refute_receive "{\"message\":\"You are logged in as a-user\"}"
+    end
+  end
+
   describe "As a User when I create a new chat room" do
     setup :connect_as_a_user