React components not loading

[abelta]

I'm using an rSpec + Capybara + Poltergeist setup to do integration tests for my React components (with react-on-rails gem).
All of my tests are failing so far because they seem to be executed at a time when the React components haven't loaded yet and I'm debugging and not getting any errors about React or ES6 not being present.
This is what my rails_helper.rb looks like (partially)

Capybara.javascript_driver = :poltergeist

Capybara.register_driver :poltergeist do |app|
    options = {
              js_errors: true,
              timeout: 500, # adjusts timeout in ms
              debug: true,
              phantomjs_options: %w{--ignore-ssl-errors=yes --ssl-protocol=TLSv1}
              }
  Capybara::Poltergeist::Driver.new(app, options)
end

I know components are not loaded for a test because I've seen it in the screenshots I get with save_screenshot.
Is there a known way to do this?

[twalpole]

Make 100% sure your code is being transpiled to ES5 (or not using any JS features beyond that). Unfortunately PhantomJS may silently just not run JS if it fails at parse time (using JS features like let etc - #823 ). Beyond that you'd need to show an actual test that fails. Closing for now we can reopen if more info is provided and this is actually an issue with Poltergeist.