ConversationView: fix last_status.account being empty, fix current user being included in group conversations

lib/pleroma/web/mastodon_api/views/conversation_view.ex

@@ -34,14 +34,22 @@ def render("participation.json", %{participation: participation, for: user}) do
 
     activity = Activity.get_by_id_with_object(last_activity_id)
 
+    # Conversations return all users except current user when current user is not only participant
+    users = if length(participation.recipients) > 1 do
+      Enum.reject(participation.recipients, &(&1.id == user.id))
+    else
+      participation.recipients
+    end
+
     %{
       id: participation.id |> to_string(),
-      accounts: render(AccountView, "index.json", users: participation.recipients, for: user),
+      accounts: render(AccountView, "index.json", users: users, for: user),
       unread: !participation.read,
       last_status:
         render(StatusView, "show.json",
           activity: activity,
-          direct_conversation_id: participation.id
+          direct_conversation_id: participation.id,
+          for: user
         )
     }
   end

test/pleroma/web/mastodon_api/controllers/conversation_controller_test.exs

@@ -54,16 +54,37 @@ test "returns correct conversations", %{
              ] = response
 
       account_ids = Enum.map(res_accounts, & &1["id"])
-      assert length(res_accounts) == 3
-      assert user_one.id in account_ids
+      assert length(res_accounts) == 2
+      assert user_one.id not in account_ids
       assert user_two.id in account_ids
       assert user_three.id in account_ids
       assert is_binary(res_id)
       assert unread == false
       assert res_last_status["id"] == direct.id
+      assert res_last_status["account"]["id"] == user_one.id
       assert Participation.unread_count(user_one) == 0
     end
 
+    test "special behaviour when conversation have only one user", %{
+      user: user_one,
+      user_two: user_two,
+      conn: conn
+    } do
+      {:ok, direct} = create_direct_message(user_one, [])
+
+      res_conn = get(conn, "/api/v1/conversations")
+
+      assert response = json_response_and_validate_schema(res_conn, 200)
+      assert [
+               %{
+                 "accounts" => res_accounts,
+                 "last_status" => res_last_status
+               }
+             ] = response
+      assert length(res_accounts) == 1
+      assert res_accounts[0]["id"] == user_one.id
+    end
+
     test "observes limit params", %{
       user: user_one,
       user_two: user_two,