!7

import java.nio.file.*;
import static java.nio.file.StandardWatchEventKinds.*;

p {
  File dir = programDir();
  deleteAllProgramFiles();
  makeProgramDir();
  final Path path = dir.toPath();
  
  final WatchService watchService = FileSystems.getDefault().newWatchService();
  final WatchKey watchKey = path.register(watchService, ENTRY_CREATE, ENTRY_DELETE, ENTRY_MODIFY, OVERFLOW);
  
  thread {
    sleepSeconds(2);
    saveProgramTextFile("bla", "1");
    sleepSeconds(1);
    //watchKey.cancel();
    watchService.close();
  }
  
  final new Set<S> changes;
  final Countdown countdown = fiveSeconds();
  print("Waiting");
  expectException(ClosedWatchServiceException.class, r {
    while (!countdown.done()) {
      final WatchKey wk = watchService.take();
      print("Key taken");
      
      for (WatchEvent<?> event : wk.pollEvents()) pcall {
        final Path changed = (Path) event.context();
        print("Changed: " + changed + ", " + event.kind());
        changes.add(changed.toFile().getName());
      }
      
      bool valid = wk.reset();
      if (!valid)
        print("Key has been unregistered");
    }
  });
    
  //watchService.close();
  bool ok = eq(changes, lithashset("bla", "bla_temp"));
  print("Self-Test: " + ok);
}

Began life as a copy of #1013732