Fix Oban job and do test it

apps/transport/lib/jobs/outdated_data_notification_job.ex

@@ -1,9 +1,15 @@
 defmodule Transport.Jobs.OutdatedDataNotificationJob do
+  @moduledoc """
+  This module is in charge of sending notifications to both admins and users when data is outdated.
+  It is (currently) using the old DataChecker module, where there is also code for checking active/inactive datasets.
+  Behaviour of this job is tested in test/transport/data_checker_test.exs.
+  """
   use Oban.Worker, max_attempts: 3, tags: ["notifications"]
 
   @impl Oban.Worker
 
   def perform(%Oban.Job{id: job_id}) do
     Transport.DataChecker.outdated_data(job_id)
+    :ok
   end
 end

apps/transport/lib/transport/data_checker.ex

@@ -1,6 +1,8 @@
 defmodule Transport.DataChecker do
   @moduledoc """
-  Use to check data, and act about it, like send email
+  Use to check data for two things:
+  - Toggle in and of active status of datasets depending on status on data.gouv.fr
+  - Send notifications to producers and admins when data is outdated
   """
   alias DB.{Dataset, Repo}
   import Ecto.Query

apps/transport/test/transport/data_checker_test.exs

@@ -3,6 +3,7 @@ defmodule Transport.DataCheckerTest do
   import Mox
   import DB.Factory
   import Swoosh.TestAssertions
+  use Oban.Testing, repo: DB.Repo
 
   doctest Transport.DataChecker, import: true
 
@@ -233,7 +234,7 @@ defmodule Transport.DataCheckerTest do
         dataset_id: dataset.id
       })
 
-      Transport.DataChecker.outdated_data(42)
+      assert :ok == perform_job(Transport.Jobs.OutdatedDataNotificationJob, %{})
 
       # a first mail to our team
 
@@ -271,7 +272,7 @@ defmodule Transport.DataCheckerTest do
     end
 
     test "outdated_data job with nothing to send should not send email" do
-      Transport.DataChecker.outdated_data(42)
+      assert :ok == perform_job(Transport.Jobs.OutdatedDataNotificationJob, %{})
       assert_no_email_sent()
     end
   end