//one level
sheet.groupColumn((short) 2, (short) 7);
sheet.groupColumn((short) 10, (short) 11);
CTCols cols = sheet.getCTWorksheet().getColsArray(0);
assertEquals(2, cols.sizeOfColArray());
CTCol[] colArray = cols.getColArray();
assertNotNull(colArray);
assertEquals(2 + 1, colArray[0].getMin()); // 1 based
assertEquals(7 + 1, colArray[0].getMax()); // 1 based
assertEquals(1, colArray[0].getOutlineLevel());