CodeSearch survey: https://codesearch.wmcloud.org/deployed/?q=public+function+provide*&files=tests%2F&excludeFiles=&repos=
In the spirit of T332865: PHPUnit data providers should be simple static functions that return plain data, we've mostly migrated our code to use pure data providers, but there are still some extensions (per code search) above that still don't follow this pattern.
It would be nice to migrate all of them to the new pattern. Not sure if it would be helpful to tag all extensions on the codesearch list.