cellB1.setCellValue(10);
XSSFFormulaEvaluator formulaEvaluator = wb.getCreationHelper().createFormulaEvaluator();
cellA2.setCellFormula("IF(B1=0,\"\",((ROW()-ROW(A$1))*12))");
CellValue evaluate = formulaEvaluator.evaluate(cellA2);
System.out.println(evaluate);
assertEquals("12.0", evaluate.formatAsString());
cellA2.setCellFormula("IF(NOT(B1=0),((ROW()-ROW(A$1))*12),\"\")");
CellValue evaluateN = formulaEvaluator.evaluate(cellA2);
System.out.println(evaluateN);