### Question:
BaseFineIoWriter implements Writer { @Override public void release() { IoUtil.close(writeFile, appendFile); } BaseFineIoWriter(boolean isOverwrite); @Override void release();  }### Answer:
@Test public void release() { BaseFineIoWriter fineIoWriter = mock(BaseFineIoWriter.class, CALLS_REAL_METHODS); fineIoWriter.writeFile = mock(IWriteFile.class); fineIoWriter.release(); verify(fineIoWriter.writeFile).close(); }