### Question:
TagExtractor { public String closeTag() { String st = null; if (tag_ == target_ && buf_.length() > threshold_) { st = buf_.toString(); ++count_; } clear(); return st; } TagExtractor(String tag, int threshold); int count(); void clear(); void setTag(String tag); void add(String line); String closeTag();  }### Answer:
@Test public final void testCloseTag() { TagExtractor extractor = new TagExtractor(null, 0); extractor.closeTag(); }