@Test
public void testRollingCountTrue() {

  Boolean[] data = new Boolean[] {true, false, false, true, true};
  BooleanColumn booleanColumn = BooleanColumn.create("data", data);
  DoubleColumn result = (DoubleColumn) booleanColumn.rolling(2).calc(countTrue);
  assertEquals(Double.NaN, result.getDouble(0), 0.0);
  assertEquals(1, result.getDouble(1), 0.0);
  assertEquals(0, result.getDouble(2), 0.0);
  assertEquals(1, result.getDouble(3), 0.0);
  assertEquals(2, result.getDouble(4), 0.0);
}