*/
private void assertRewrite(String origSrc, String expectedRewrittenSrc) throws Exception {
ExprNode expr = (new ExpressionParser(origSrc)).parseExpression();
(new RewriteNullCoalescingOpInExprVisitor()).exec(expr);
String rewrittenSrc = expr.toSourceString();
assertEquals(expectedRewrittenSrc, rewrittenSrc);
}
}