### Question:
DumpFileWriter { public void writeHeaderOnly() { int size = tableDesc.getColumnDescList().size(); StringBuilder buf = new StringBuilder(size * 10); for (ColumnDesc columnDesc : tableDesc.getColumnDescList()) { if (isIgnoreColumn(columnDesc)) { continue; } String columnName = columnDesc.getName(); buf.append(DumpUtil.quote(columnName)); buf.append(delimiter); } if (buf.length() > 0) { buf.setLength(buf.length() - 1); } writeLine(buf.toString()); } DumpFileWriter(File dumpFile, TableDesc tableDesc,
            GenDialect dialect, String encoding, char delimiter); void writeHeaderOnly(); void writeRows(ResultSet rs); void close(); int getLineNumber();  }### Answer:
@Test public void testWriteHeaderOnly() throws Exception { dumpFileWriter.writeHeaderOnly(); bufferedWriter.flush(); assertEquals(1, dumpFileWriter.getLineNumber()); assertEquals("\"aaa\",\"bbb\",\"ccc\"" + separator, stringWriter .toString()); }