ActionDispatch::SystemTestCase no longer inherits from ActionDispatch::IntegrationTest in Rails 6.0.1

With Rails Release 6.0.1, ActionPack comes with this breaking change:

ActionDispatch::SystemTestCase now inherits from ActiveSupport::TestCase rather than ActionDispatch::IntegrationTest

Link to CHANGELOG

That means that some useful helper methods won’t be available anymore in system tests.

In one project we use a method fixture_file_upload that was affected by this change. We brought this back by including the corresponding module in ApplicationSystemTestCase:

class ApplicationSystemTestCase < ActionDispatch::SystemTestCase
  include ActionDispatch::TestProcess::FixtureFile

  # ...
end