Upgrade DatabaseCleaner strategy

spec/controllers/code_ocean/files_controller_spec.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'rails_helper'
 
 describe CodeOcean::FilesController do
@@ -48,6 +50,8 @@ describe CodeOcean::FilesController do
       expect { perform_request.call }.to change(CodeOcean::File, :count).by(-1)
     end
 
-    expect_redirect(:exercise)
+    it 'redirects to exercise path' do
+      expect(controller).to redirect_to(exercise)
+    end
   end
 end

spec/controllers/exercises_controller_spec.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'rails_helper'
 
 describe ExercisesController do
@@ -230,8 +232,8 @@ describe ExercisesController do
   describe 'POST #submit' do
     let(:output) { {} }
     let(:perform_request) { post :submit, format: :json, params: { id: exercise.id, submission: {cause: 'submit', exercise_id: exercise.id} } }
-    let!(:external_user) { FactoryBot.create(:external_user) }
-    let!(:lti_parameter) { FactoryBot.create(:lti_parameter, external_user: external_user, exercise: exercise) }
+    let(:user) { FactoryBot.create(:external_user) }
+    let!(:lti_parameter) { FactoryBot.create(:lti_parameter, external_user: user, exercise: exercise) }
 
     before(:each) do
       allow_any_instance_of(Submission).to receive(:normalized_score).and_return(1)

spec/support/database_cleaner.rb

@@ -1,10 +1,48 @@
+# frozen_string_literal: true
+
+require 'capybara/rspec'
+
 RSpec.configure do |config|
+
+  config.use_transactional_fixtures = false
+
   config.before(:suite) do
-    DatabaseCleaner.strategy = :truncation
+    if config.use_transactional_fixtures?
+      raise(<<-MSG)
+        Delete line `config.use_transactional_fixtures = true` from rails_helper.rb
+        (or set it to false) to prevent uncommitted transactions being used in
+        JavaScript-dependent specs.
+
+        During testing, the app-under-test that the browser driver connects to
+        uses a different database connection to the database connection used by
+        the spec. The app's database connection would not be able to access
+        uncommitted transaction data setup over the spec's database connection.
+      MSG
+    end
+
     DatabaseCleaner.clean_with(:truncation)
   end
 
-  config.around(:each) do |example|
-    DatabaseCleaner.cleaning { example.run }
+  config.before do
+    DatabaseCleaner.strategy = :transaction
+  end
+
+  config.before(:each, type: :feature) do
+    # :rack_test driver's Rack app under test shares database connection
+    # with the specs, so continue to use transaction strategy for speed.
+    unless Capybara.current_driver == :rack_test
+      # Driver is probably for an external browser with an app
+      # under test that does *not* share a database connection with the
+      # specs, so use truncation strategy.
+      DatabaseCleaner.strategy = :truncation
+    end
+  end
+
+  config.before do
+    DatabaseCleaner.start
+  end
+
+  config.append_after do
+    DatabaseCleaner.clean
   end
 end