public void failExpression(String expression, String matchException) throws Exception {
boolean[] flags = { engine.isLenient(), engine.isSilent() };
try {
engine.setLenient(false);
engine.setSilent(false);
Expression exp = engine.createExpression(expression);
exp.evaluate(context);
fail("expression: " + expression);
} catch(JexlException xjexl) {
if (matchException != null && !xjexl.getMessage().matches(matchException)) {
fail("expression: " + expression + ", expected: " + matchException + ", got " + xjexl.getMessage());
}