As one of the instrumentations for ToC ( table of content), Web team will deploy the instrumentation to enable AB test on the table of content. (T302046)
== Instrumentation note
The test group enrollment events are stored in `mediawiki_web_ab_test_enrollment` schema.
As of 2022-04-27, user bucketing is based on what page user lands on first, and then persistent for that session. The page_id of the landing page is the salt to decide which test group the session will be in. Session_id is used to identify user session, stored in field `web_session_id`.
**Test population**: logged in users and anonymous users
**Group split**: Sample entire population, 50% to control group, 50% to test group.
== QA summary
=== Bugs/Potential Issues
|Issue | Status | Note |
|----|-----|-----|
|web_pageview_id is NULL |❓ | In current AB test instrument, we randomize sessions by the page_id of the landing page. Should we also record the page_id for the purpose of data sanity check and analysis? |