### Question:
SnapStream { public static boolean isValidSnapshot(File file) throws IOException { if (file == null || Util.getZxidFromName(file.getName(), FileSnap.SNAPSHOT_FILE_PREFIX) == -1) { return false; } boolean isValid = false; switch (getStreamMode(file.getName())) { case GZIP: isValid = isValidGZipStream(file); break; case SNAPPY: isValid = isValidSnappyStream(file); break; case CHECKED: default: isValid = isValidCheckedStream(file); } return isValid; }  static CheckedInputStream getInputStream(File file); static CheckedOutputStream getOutputStream(File file, boolean fsync); static void sealStream(CheckedOutputStream os, OutputArchive oa); static boolean isValidSnapshot(File file); static void setStreamMode(StreamMode mode); static StreamMode getStreamMode(); static StreamMode getStreamMode(String fileName); static final String ZOOKEEPER_SHAPSHOT_STREAM_MODE; }### Answer:
@Test public void testInvalidSnapshot() throws IOException { assertFalse(SnapStream.isValidSnapshot(null)); checkInvalidSnapshot("snapshot.180000e3a2"); checkInvalidSnapshot("snapshot.180000e3a2.gz"); checkInvalidSnapshot("snapshot.180000e3a2.snappy"); }