@Test
public void testCountMissing() {

  DoubleColumn doubles = DoubleColumn.create("doubles");
  for (int i = 0; i < 10; i++) {
    doubles.append(RandomUtils.nextDouble(0, 1_000));
  }
  assertEquals(0, doubles.countMissing());
  doubles.clear();
  for (int i = 0; i < 10; i++) {
    doubles.append(MISSING);
  }
  assertEquals(10, doubles.countMissing());
}