Couldn't find documentation for this but eventually figured it out.
Note: Verified with 23H2 VHLK
For the ApiValidator test to populate the QueryValidateDriverFolder parameter:
- open HLK Studio
- create your project in the project tab
- select your driver in the selection tab
- click "add driver folder" in the package tab.
- the driver in that folder must match the fingerprint of the driver installed in the driver store on the test machine
- the folder needs to be added before you run the test on that driver
- select and run the apivalidator test
If you would like to test a new version of the driver in the same project:
- remove the driver from the selection tab (which deletes all associated test results)
- install the new driver version on the test machine
- restart HLK studio
- reselect your driver in the selection tab
- verify that the driver folder in the package tab has the correct driver version
- rerun the apivalidator test