### Question:
ContentExtractor { public void traverse(Receiver e) { int numberOfPages = reader.getNumberOfPages(); for (int pageNum = 1; pageNum <= numberOfPages; pageNum++) { List<String> pageContent = getPageContent(pageNum); if (pageContent != null && !pageContent.isEmpty() && e != null) { e.process(pageNum, pageContent); } } } private  ContentExtractor();  ContentExtractor(OFDReader reader); List<String> getPageContent(int pageNum); List<String> extractAll(); void traverse(Receiver e);  }### Answer:
@Test void traverse() throws IOException { try (OFDReader reader = new OFDReader(src)) { ContentExtractor extractor = new ContentExtractor(reader); extractor.traverse((pageNum, contents) -> { assertEquals(contents.size(), 1); assertEquals("你好呀，OFD Reader&Writer！", contents.get(0)); }); } }