### Question:
GlusterPath implements Path { void guardRegisterWatchService(WatchService watchService) { Class<? extends WatchService> watchServiceClass = watchService.getClass(); if (!GlusterWatchService.class.equals(watchServiceClass)) { throw new UnsupportedOperationException("GlusterPaths can only be watched by GlusterWatchServices. WatchService given: " + watchServiceClass); } } GlusterPath(GlusterFileSystem fileSystem, String path);   GlusterPath(GlusterFileSystem fileSystem, String[] parts, boolean absolute); @Override boolean isAbsolute(); @Override Path getRoot(); @Override Path getFileName(); @Override Path getParent(); @Override int getNameCount(); @Override Path getName(int i); @Override Path subpath(int i, int i2); @Override boolean startsWith(Path path); @Override boolean startsWith(String s); @Override boolean endsWith(Path path); @Override boolean endsWith(String s); @Override Path normalize(); @Override Path resolve(Path path); @Override Path resolve(String s); @Override Path resolveSibling(Path path); @Override Path resolveSibling(String s); @Override Path relativize(Path path); @Override URI toUri(); @Override Path toAbsolutePath(); @Override Path toRealPath(LinkOption... linkOptions); @Override File toFile(); @Override WatchKey register(WatchService watchService, WatchEvent.Kind<?>[] kinds, WatchEvent.Modifier... modifiers); @Override WatchKey register(WatchService watchService, WatchEvent.Kind<?>... kinds); @Override Iterator<Path> iterator(); @Override int compareTo(Path path); String toString(); String getString();  }### Answer:
@Test(expected = UnsupportedOperationException.class) public void testGuardRegisterWatchService() { GlusterPath path = spy(new GlusterPath(mockFileSystem, new String[]{}, false)); WatchService mockWatchService = mock(WatchService.class); path.guardRegisterWatchService(mockWatchService); }