Function test_rewrite

datafusion/expr/src/expr_rewriter/mod.rs:556–582

rewrites `expr_from` to `rewrite_to` while preserving the original qualified name by using the `NamePreserver`

(expr_from: Expr, rewrite_to: Expr)

    /// rewrites `expr_from` to `rewrite_to` while preserving the original qualified name
    /// by using the `NamePreserver`
    fn test_rewrite(expr_from: Expr, rewrite_to: Expr) {
        struct TestRewriter {
            rewrite_to: Expr,
        }

        impl TreeNodeRewriter for TestRewriter {
            type Node = Expr;

            fn f_up(&mut self, _: Expr) -> Result<Transformed<Expr>> {
                Ok(Transformed::yes(self.rewrite_to.clone()))
            }
        }

        let mut rewriter = TestRewriter {
            rewrite_to: rewrite_to.clone(),
        };
        let saved_name = NamePreserver { use_alias: true }.save(&expr_from);
        let new_expr = expr_from.clone().rewrite(&mut rewriter).unwrap().data;
        let new_expr = saved_name.restore(new_expr);

        let original_name = expr_from.qualified_name();
        let new_name = new_expr.qualified_name();
        assert_eq!(
            original_name, new_name,
            "mismatch rewriting expr_from: {expr_from} to {rewrite_to}"
        )
    }
}