Thank you very much for your help, with the above I have been able to pass the test successfully. But I found that I still have the earth translation icon.
root@talk-app:/var/www/discourse/plugins/discourse-translator/services/discourse_translator# rails c
[1] pry(main)> DiscourseTranslator::Google.detect(Post.last)
=> "en"
[2] pry(main)>