add presence client behaviour callbacks

lib/live_beats/presence/phoenix_presence_client.ex

@@ -1,6 +1,10 @@
 defmodule Phoenix.Presence.Client do
   use GenServer
 
+  @callback init(state :: term) :: {:ok, new_state :: term}
+  @callback handle_join(topic :: String.t(), key :: String.t(), meta :: [map()], state :: term) :: {:ok, term}
+  @callback handle_leave(topic :: String.t(), key :: String.t(), meta :: [map()], state :: term) :: {:ok, term}
+
   @doc """
   TODO
 

lib/live_beats/presence/presence_client.ex

@@ -4,19 +4,17 @@ defmodule LiveBeats.PresenceClient do
   @presence LiveBeatsWeb.Presence
   @pubsub LiveBeats.PubSub
 
-  def start_link(opts) do
-    Phoenix.Presence.Client.start_link(presence: @presence, client: __MODULE__)
-  end
-
   def list(topic) do
     @presence.list(topic)
   end
 
+  @impl Phoenix.Presence.Client
   def init(_opts) do
     # user-land state
     {:ok, %{}}
   end
 
+  @impl Phoenix.Presence.Client
   def handle_join(topic, key, _meta, state) do
     active_users_topic =
       topic
@@ -28,6 +26,7 @@ defmodule LiveBeats.PresenceClient do
     {:ok, state}
   end
 
+  @impl Phoenix.Presence.Client
   def handle_leave(topic, key, _meta, state) do
     active_users_topic =
       topic

test/support/presence/client_mock.ex

@@ -5,12 +5,10 @@ defmodule Phoenix.Presence.Client.Mock do
   end
 
   def handle_join(_topic, _key, _meta, state) do
-    IO.inspect(:handle_join)
     {:ok, state}
   end
 
   def handle_leave(_topic, _key, _meta, state) do
-    IO.inspect(:handle_leave)
     {:ok, state}
   end
 

test/support/presence/presence_mock.ex

@@ -18,7 +18,6 @@ defmodule Phoenix.Presence.Client.PresenceMock do
 
   @impl true
   def handle_info(:quit, state) do
-    IO.inspect(:quit)
     {:stop, :normal, state}
   end