TL;DR SEO test
Does Google support noindex in robots.txt?
This is what Google’s John Mueller said:
We don’t officially support it, so I wouldn’t rely on any particular effect.— 🍌 John 🍌 (@JohnMu) April 17, 2019
There is obviously a difference between ‘officially support’ and support. Gary Illyes apparenty is going to be “cleaning up that part of the googlebot codebase”, to remove the unofficial support.
This may go away. I’m cleaning up that part of the googlebot codebase nowadays and that thing sticks out like a nun in a mosh pit— Gary “鯨理” Illyes (@methode) April 18, 2019
So it might be helpful to have this page here as a canary in the mine. The current result of this test is: