Drive_test_####... files. What are they?

I have a question
1

I have suddenly had files with the name drive_test_##########_########## (i.e. 10 plus 9 or 10 digits) appearing in the .sync folder of one of my ‘Boxified’ folders. They are appearing at 10 minute intervals. Does anyone know what they are and why they have started appearing?

Thanks.

2

Boxifier does not create any files with that pattern so it must be another software that is writing those files.

Maybe this could be the software that is creating those files.