### Question:
RawBackupWriter implements BackupWriter { @Override public void writeChunk(long start, int length) throws IOException { throw new UnsupportedOperationException("RawBackupWriter cannot write existing chunks"); } RawBackupWriter(OutputStream outputStream); @Override void writeBytes(byte[] bytes); @Override void writeChunk(long start, int length); @Override long getBytesWritten(); @Override void flush();  }### Answer:
@Test public void writeChunk_throwsUnsupportedOperationException() throws Exception { assertThrows(UnsupportedOperationException.class, () -> mWriter.writeChunk(0, 0)); }