Drupal Major Upgrade Validation

Validate a Drupal major version upgrade by capturing a behavioral baseline on the current stable version, applying the upgrade, and running the same tests again on the new version. Produce a structured comparison report.

This skill is project-agnostic. It discovers how to run commands, which containers to use, and what URLs to hit by reading the project's AGENTS.md and other skills loaded in the current session.

Before You Start

Prerequisites

1. Two branches must exist: a stable branch (e.g., develop) running the current Drupal major version, and an upgrade branch with the new version already prepared (dependencies updated, patches ported, configuration adjusted).