### Question:
RocksUtils { public static void close(AbstractImmutableNativeReference ref) { if (null == ref) { return; } ref.close(); }  static void close(AbstractImmutableNativeReference ref); static boolean isSstFile(File file); static String getDestCheckpointsPath(String dbPrefix); static String getDestCheckpointPath(String dbPrefix, String checkpointId); static String getDestCheckpointMetadataPath(String dbPrefix, String checkpointId); static String getDestSstsPath(String dbPrefix); static String getDestSstPath(String dbPrefix, File file); static String getDestSstPath(String dbPrefix, String fileName); static String getDestTempSstPath(String dbPrefix, String checkpointId, File file); static String getDestPath(String dbPrefix,
                                     String checkpointId,
                                     File file);  }### Answer:
@Test public void testCloseNull() { RocksUtils.close(null); assertTrue(true); }
@Test public void testClose() { AbstractImmutableNativeReference ref = mock(AbstractImmutableNativeReference.class); RocksUtils.close(ref); verify(ref, times(1)).close(); }