add a test ensuring that we only dump screenshots for minitest cases derived from ActionDispatch::IntegrationTest
add a test ensuring that we only dump screenshots for minitest cases derived from ActionDispatch::IntegrationTest

BentPixels/capybara-screenshot,HealthTeacher/capybara-screenshot,Patru/capybara-screenshot,chendrix/capybara-screenshot,mattheworiordan/capybara-screenshot,xuwupeng2000/capybara-screenshot