Starting a new macro for comparing fields.

This will help us assert that all fields are tested and that only expected fields are present.

src/compare/diff.rs

@@ -13,6 +13,8 @@ use super::util::get_property_boolean;
 use super::util::get_property_numeric;
 use super::util::get_property_quoted_string;
 use super::util::get_property_unquoted_atom;
+use crate::compare::elisp_fact::EmacsField;
+use crate::compare::macros::compare_properties;
 use crate::types::AngleLink;
 use crate::types::AstNode;
 use crate::types::BabelCall;
@@ -2688,6 +2690,9 @@ fn compare_code<'b, 's>(
         ));
     }
 
+    let foo: Result<Option<(DiffStatus, Option<String>)>, Box<dyn std::error::Error>> =
+        compare_properties!(emacs, EmacsField::Required(":value"));
+
     Ok(DiffResult {
         status: this_status,
         name: rust.get_elisp_name(),