Discovery and definition

As part of the work to T390553: Support default values when fields are left blank for date inputs in the Wikifunctions integration so that editors can use it more simply we have noticed the following mismatch:

According to the design prototype, the Function description contains all the information about its use and the expected behavior with blank values, e.g.:

"Returns the number of full years between two specific dates. If the second parameter is not included it uses today's date"

However the implementation of default values feature does not lie in Wikifunctions, but is part of the integration into Wikipedia. This means that a Wikifunctions user that visits the page for the "age" function, even if they see this behavior in the description, they won't be able to call the age function with an empty argument, nor they will be able to create tests for this edge case.

Research and plan

• Investigate possible drawbacks of this documentation discrepancy and suggest a way forward, which might just involve proper communication to the Wikifunctions community, a different UX solution, or even just ignoring the issue and collecting feedback after the rollout.

Completion checklist
Before closing this task, review one by one the checklist available here: https://www.mediawiki.org/wiki/Abstract_Wikipedia_team/Definition_of_Done#Design_task_completion_checklist