This adds two new text tags for unit frames, PartyIndex and RaidIndex, which correspond to the unit index in the party or raid. This is mostly a debug feature to be able to differentiate party frames from each other so that it is easier to test other features with the test mode.
A few comments about the implementation, since this was done quickly, expecting some feedback on how to contribute:
The implementation differs between party and raid because there is a UnitInRaid function but no its equivalent for party. Maybe it would be better to have them more similar, either by implementing UnitInParty (already exists but return a boolean, while UnitInRaid returns the member index) or parsing the unit name in the RaidIndex tag.
Group and raid sizes are hardcoded, because they are also hardcoded in existing code in test mode for party and raid. It would probably be better to use a variable for that.
Raid member index appears to not depend on the member location in the raid groups. I noticed the raid layout collapses groups (so all members are in sequence instead of in groups), I don't know if there is a way to work around that.
I made these changes before looking into the party vertical orientation being bottom to top instead of the reverse. I was thinking about other utilities for the test mode, such as randomizing frames to check the appearance (color and other stuff), but probably for later.
This adds two new text tags for unit frames, PartyIndex and RaidIndex, which correspond to the unit index in the party or raid. This is mostly a debug feature to be able to differentiate party frames from each other so that it is easier to test other features with the test mode.