- test.py generates its own test files in test_data/ (small.txt, medium.txt,
binary.bin, nested subtree)
- source and dest directories configurable via --source-dir / --dest-dir
- verifies all transferred files match originals byte-for-byte after each test
- waits for server to finish before verification (fixes race in multithreaded)
- all test data lives under test_data/ and is cleaned up unless --keep-data