add uniq index on attestation dossier_id

db/migrate/20220405100354_add_uniq_index_on_attestation_dossier_id.rb

@@ -0,0 +1,9 @@
+class AddUniqIndexOnAttestationDossierId < ActiveRecord::Migration[6.1]
+  include Database::MigrationHelpers
+  disable_ddl_transaction!
+
+  def up
+    remove_index :attestations, :dossier_id
+    add_concurrent_index :attestations, :dossier_id, unique: true
+  end
+end

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 2022_03_23_120846) do
+ActiveRecord::Schema.define(version: 2022_04_05_100354) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
@@ -134,7 +134,7 @@ ActiveRecord::Schema.define(version: 2022_03_23_120846) do
     t.integer "dossier_id", null: false
     t.string "title"
     t.datetime "updated_at", null: false
-    t.index ["dossier_id"], name: "index_attestations_on_dossier_id"
+    t.index ["dossier_id"], name: "index_attestations_on_dossier_id", unique: true
   end
 
   create_table "avis", id: :serial, force: :cascade do |t|

spec/models/dossier_spec.rb

@@ -1480,12 +1480,10 @@ describe Dossier do
     before do
       create(:dossier, transfer: transfer)
       create(:attestation, dossier: dossier)
-      create(:attestation, dossier: dossier)
     end
 
-    it "can destroy dossier with two attestations" do
+    it "can destroy dossier" do
       expect(dossier.destroy).to be_truthy
-      expect(transfer.reload).not_to be_nil
     end
   end