Add some tests

Also add a unicity constraint on the followers table

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

priv/repo/migrations/20180802133951_make_follower_table_unique.exs

@@ -0,0 +1,11 @@
+defmodule Eventos.Repo.Migrations.MakeFollowerTableUnique do
+  use Ecto.Migration
+
+  def up do
+    create unique_index(:followers, [:actor_id, :target_actor_id], name: :followers_actor_target_actor_unique_index)
+  end
+
+  def down do
+    drop index(:followers, [:actor_id, :target_actor_id], name: :followers_actor_target_actor_unique_index)
+  end
+end