The CTT writes the minimum value to the first configured scalar item in the afterTests.js without reverting it.
In most of the cases this would/should be a Boolean, but it can be any of the other DataTypes too.

Proposed solution:

• Reading the value before writing it
• Using UaVariant.Increment() instead of UaVariant.Min()
• Reverting the value if the first write succeeds

... or even simplier:
Just write the same value again. At this point, the CTT is not testing the functionality, but is only interested if the server returns Bad_ServiceUnsupported.

A Read before the Write has been added and the CTT now writes the same value to the item again.
Because the CTT is only interested in the ServiceResult and not in testing the functionality, the written value is not important.