Add some tests

Also add a unicity constraint on the followers table

Signed-off-by: Thomas Citharel <tcit@tcit.fr>

lib/eventos/actors/follower.ex

@@ -19,5 +19,6 @@ defmodule Eventos.Actors.Follower do
     member
     |> cast(attrs, [:score, :approved, :target_actor_id, :actor_id])
     |> validate_required([:score, :approved, :target_actor_id, :actor_id])
+    |> unique_constraint(:target_actor_id, name: :followers_actor_target_actor_unique_index)
   end
 end