During the lead paragraph work we began a refactor of the MobileFormatter class for best testability and readability.
Code coverage of the new transforms is good:
https://doc.wikimedia.org/cover-extensions/MobileFrontend/transforms/index.html
https://doc.wikimedia.org/cover-extensions/MobileFrontend/MobileFormatter.php.html
= Work (incomplete)
[X] Separate the LazyLoadedImages transform from MobileFormatter (https://gerrit.wikimedia.org/r/448415)
[x] Separate the LegacyMainPage transform from MobileFormatter (https://gerrit.wikimedia.org/r/#/401786)
[x] Add tests for AddMobileTocTransform
[x] Separate out the RemoveImagesTransform from MobileFormatter and mark as @deprecated referencing T186627 (https://gerrit.wikimedia.org/r/620716)
[] Separate out the MobileSectionTransform transform from MobileFormatter
# Sign off steps
[] MobileContext contains many methods which should be migrated to the MobileFormatter - for example, [get|set]ContentTransformations. Review and port as appropriate. Create tasks.
[] Review remaining transforms and their purpose (are they redundant?) . Create tasks.