in HWUT (hello world unit test), how can I change the maximal size of a test output file. Currently it seems to be limited to 1kB.
The default limit is 1MB which is reasonable. You can adapt the maximum output file size by means of the environment variable
But be careful! The size limit exists to prevent the test application from spamming you hard drive with nonsense data. A loopy freaked-out test application may very well stall your computer if it flushes so badly that no more space for others remains.
Also, while HWUT can be very flexible during output comparison, I doubt that more than 1MB of content can be judged appropriately. Maybe, filtering the output would make sense.