* Create new class called ApplicationIntegrationTest, so we don't have
to override ActionDispatch::IntegrationTest
* Move UI tests to inherit from ApplicationSystemTestCase
* Existing REST API or EPP tests inherit from
ApplicationIntegrationTest.
* Move `require 'application_system_test_case'` at the end of
`test_helper`
I don't particularly agree with the Rails' convention of treating UI
tests as system tests and API tests as integration tests, but I see no
benefit in actively fighting against it.
In the future, ApplicationSystemTestCase should inherit from
ActionDispatch::SystemTestCase and JavaScriptApplicationSystemTestCase
could possibly be removed if the `driven_by` method works as it is
promised in Rails documentation:
http://api.rubyonrails.org/v5.2/classes/ActionDispatch/SystemTestCase.html
Consider introducing another class between
ActionDispatch::IntegrationTest and other items inheriting from it, as
the general Rails practice seems to have `ApplicationIntegrationTest`,
as we do have `ApplicationRecord` and `ApplicationController`.
