feat: add user validation test

spec/helpers/organisations_helper_spec.rb

@@ -1,7 +1,6 @@
 require "rails_helper"
 
 RSpec.describe OrganisationsHelper do
-
   include TagHelper
   describe "display_organisation_attributes" do
     let(:organisation) { create(:organisation) }

spec/models/user_spec.rb

@@ -334,6 +334,16 @@ RSpec.describe User, type: :model do
           .to raise_error(ActiveRecord::RecordInvalid, error_message)
       end
     end
+
+    context "when a user is added to a merged organisation" do
+      let(:merged_organisation) { create(:organisation, merge_date: Time.zone.yesterday) }
+      let(:error_message) { "Validation failed: Organisation #{I18n.t("validations.organisation.merged")}" }
+
+      it "validates email format" do
+        expect { create(:user, organisation: merged_organisation) }
+          .to raise_error(ActiveRecord::RecordInvalid, error_message)
+      end
+    end
   end
 
   describe "delete" do