fix crash when labels are added concurrently

lib/mindwendel/brainstormings/idea_idea_label.ex

@@ -21,7 +21,7 @@ defmodule Mindwendel.Brainstormings.IdeaIdeaLabel do
     |> cast_assoc(:idea, required: true)
     |> cast_assoc(:idea_label, required: true)
     |> unique_constraint([:idea_id, :idea_label_id],
-      name: :idea_idea_labels_idea_id_idea_label_id_index
+      name: :idea_idea_labels_pkey
     )
   end
 
@@ -30,7 +30,7 @@ defmodule Mindwendel.Brainstormings.IdeaIdeaLabel do
     |> cast(attrs, [:idea_id, :idea_label_id])
     |> validate_required([:idea_id, :idea_label_id])
     |> unique_constraint([:idea_id, :idea_label_id],
-      name: :idea_idea_labels_idea_id_idea_label_id_index
+      name: :idea_idea_labels_pkey
     )
   end
 end

test/mindwendel/idea_idea_label_test.exs

@@ -19,7 +19,7 @@ defmodule Mindwendel.IdeaIdeaLabelTest do
       }
     end
 
-    test "s", %{idea: idea} do
+    test "valid with idea and idea_label", %{idea: idea} do
       idea_label = idea.brainstorming.labels |> Enum.at(0)
 
       idea_idea_label_changeset =

test/mindwendel/idea_labels_test.exs

@@ -43,21 +43,12 @@ defmodule Mindwendel.IdeaLabelsTest do
       assert Repo.one(IdeaLabel) == idea_label
     end
 
-    @tag :skip
     test "does not add the same IdeaLabel twice to Idea", %{idea_label: idea_label, idea: idea} do
       # Calling this method twice does not fail and does not create duplicates
-      {:ok, idea_idea_label_after_method_call_1} =
-        IdeaLabels.add_idea_label_to_idea(idea, idea_label.id)
-
-      {:ok, idea_idea_label_after_method_call_2} =
+      {:ok, _} =
         IdeaLabels.add_idea_label_to_idea(idea, idea_label.id)
 
-      # There should still be only one IdeaIdeaLabel
-      assert Repo.count(IdeaIdeaLabel) == 1
-
-      assert Repo.count(IdeaLabel) == 1
-
-      assert idea_idea_label_after_method_call_1 == idea_idea_label_after_method_call_2
+      assert {:error, _changeset} = IdeaLabels.add_idea_label_to_idea(idea, idea_label.id)
     end
 
     @tag :skip