/** Test a null formula */
 @Test
 public void testNullFormula() {
   logger.info("Test null Formula");
   String formula = null;
   Object resObject = Formula.evalFormula(formula);
   Assert.assertNull(resObject);
 }
 /** Test an invalid formula; should return null value */
 public void testInvalidFormula() {
   logger.info("Test invalid Formula");
   String formula = "ax";
   Object resObject = Formula.evalFormula(formula);
   Assert.assertNull(resObject);
 }