fix: Duplicate team submissions being created

Author: RichDom2185

lib/cadet/jobs/autograder/grading_job.ex

@@ -135,18 +135,31 @@ defmodule Cadet.Autograder.GradingJob do
           team
         end
 
+      find_or_create_team_submission(team.id, assessment)
+    else
+      # Individual assessment
       %Submission{}
       |> Submission.changeset(%{
-        team_id: team.id,
+        student_id: student_id,
         assessment: assessment,
         status: :submitted
       })
       |> Repo.insert!()
+    end
+  end
+
+  defp find_or_create_team_submission(team_id, assessment) when is_ecto_id(team_id) do
+    submission =
+      Submission
+      |> where(team_id: ^team_id, assessment_id: ^assessment.id)
+      |> Repo.one()
+
+    if submission do
+      submission
     else
-      # Individual assessment
       %Submission{}
       |> Submission.changeset(%{
-        student_id: student_id,
+        team_id: team_id,
         assessment: assessment,
         status: :submitted
       })