@Test
  public void bytesCntToStrTest() {
    String r = "4 GB 877 MB 539 KB 903 B";
    Assert.assertEquals(r, MemUtils.bytesCntToStr(5215121287L));
  }
This method tests MemUtils.getStringMem() and MemUtils.getDataPointMem()
iotdb-core/datanode/src/test/java/org/apache/iotdb/db/utils/MemUtilsTest.java