google search – Run beta versions of sites SEO safely


We have domain.com and want to test a new site template on beta.domain.com.

What is the correct way to run a beta test without affecting SEO of the main domain.com?

In the topic SEO safe way to run beta of new site on seperate domain I found 2 recommendations:

  1. Putting a robots.txt with noindex to our beta.domain.com
  2. Canonicalizing beta.domain.com to domain.com – Why? In any case we already have the noindex flag…

Does it still actual in 2020? And do we need to register beta.domain.com in Google Webmasters Tools?