@Test
public void testGetColumnCount() {

  metadata = new IoTDBResultMetadata(null, null, false);
  boolean flag = false;
  try {
    metadata.getColumnCount();
  } catch (Exception e) {
    flag = true;
  }
  assertFalse(flag);
  flag = false;
  try {
    metadata = new IoTDBResultMetadata(Collections.emptyList(), null, false);
    metadata.getColumnCount();
  } catch (Exception e) {
    flag = true;
  }
  assertFalse(flag);
  List<String> columnInfoList = new ArrayList<>();
  columnInfoList.add("root.a.b.c");
  metadata = new IoTDBResultMetadata(columnInfoList, null, false);
  assertEquals(metadata.getColumnCount(), 1);
}