Pipeline: Add a side effects step after the transaction finishes

This is to run things like streaming notifications out, which will
sometimes need data that is created by the transaction, but is
streamed out asynchronously.

test/web/common_api/common_api_test.exs

@@ -7,6 +7,7 @@ defmodule Pleroma.Web.CommonAPITest do
   alias Pleroma.Activity
   alias Pleroma.Chat
   alias Pleroma.Conversation.Participation
+  alias Pleroma.Notification
   alias Pleroma.Object
   alias Pleroma.User
   alias Pleroma.Web.ActivityPub.ActivityPub
@@ -39,15 +40,41 @@ defmodule Pleroma.Web.CommonAPITest do
 
       {:ok, upload} = ActivityPub.upload(file, actor: author.ap_id)
 
-      {:ok, activity} =
-        CommonAPI.post_chat_message(
-          author,
-          recipient,
-          nil,
-          media_id: upload.id
-        )
+      with_mocks([
+        {
+          Pleroma.Web.Streamer,
+          [],
+          [
+            stream: fn _, _ ->
+              nil
+            end
+          ]
+        },
+        {
+          Pleroma.Web.Push,
+          [],
+          [
+            send: fn _ -> nil end
+          ]
+        }
+      ]) do
+        {:ok, activity} =
+          CommonAPI.post_chat_message(
+            author,
+            recipient,
+            nil,
+            media_id: upload.id
+          )
 
-      assert activity
+        notification =
+          Notification.for_user_and_activity(recipient, activity)
+          |> Repo.preload(:activity)
+
+        assert called(Pleroma.Web.Push.send(notification))
+        assert called(Pleroma.Web.Streamer.stream(["user", "user:notification"], notification))
+
+        assert activity
+      end
     end
 
     test "it adds html newlines" do