Automation tools can provide a head start in updating custom and contributed code in order to be Drupal 9 ready. Palantir.net is committed to increasing the coverage of these tools and is welcoming contributions.
Manually addressing deprecations in custom and contributed code is the most challenging part of upgrading to Drupal 9 and affects nearly every Drupal 8 site. The process is often more challenging than finding a deprecated function and replacing it with a new one; the challenge comes from learning how to use the new systems. Automation can help jump-start code updates as well as help developers learn to use these new systems. The Php community has built a tool called Rector which automates a lot of this work. Palantir.net has started building off of a community proof-of-concept called Rector for Drupal. We’ll talk about how to use the tool, how to build Rectors, and how to identify high-priority deprecated features.