Compare the additional properties on headlines.

src/compare/compare_field.rs

@@ -32,6 +32,26 @@ pub(crate) enum ComparePropertiesResult<'b, 's> {
     DiffEntry(DiffEntry<'b, 's>),
 }
 
+impl<'b, 's> ComparePropertiesResult<'b, 's> {
+    pub(crate) fn apply(
+        self,
+        child_status: &mut Vec<DiffEntry<'b, 's>>,
+        this_status: &mut DiffStatus,
+        message: &mut Option<String>,
+    ) {
+        match self {
+            ComparePropertiesResult::NoChange => {}
+            ComparePropertiesResult::SelfChange(new_status, new_message) => {
+                *this_status = new_status;
+                *message = new_message
+            }
+            ComparePropertiesResult::DiffEntry(diff_entry) => child_status.push(diff_entry),
+        }
+
+        // foo
+    }
+}
+
 /// Do no comparison.
 ///
 /// This is for when you want to acknowledge that a field exists in the emacs token, but you do not have any validation for it when using the compare_properties!() macro. Ideally, this should be kept to a minimum since this represents untested values.

src/compare/diff.rs

@@ -21,6 +21,7 @@ use super::elisp_fact::GetElispFact;
 use super::sexp::unquote;
 use super::sexp::Token;
 use super::util::assert_no_children;
+use super::util::compare_additional_properties;
 use super::util::compare_children;
 use super::util::compare_children_iter;
 use super::util::compare_standard_properties;
@@ -537,12 +538,27 @@ fn compare_heading<'b, 's>(
     let mut child_status = Vec::new();
     let mut message = None;
 
-    // TODO: Add checks to compare values for additional properties.
     let additional_property_names: Vec<String> = rust
         .get_additional_properties()
         .map(|node_property| format!(":{}", node_property.property_name.to_uppercase()))
         .collect();
 
+    let additional_properties: Vec<(String, &str)> = rust
+        .get_additional_properties()
+        .map(|node_property| {
+            (
+                format!(":{}", node_property.property_name.to_uppercase()),
+                node_property.value.unwrap_or(""),
+            )
+        })
+        .collect();
+
+    compare_additional_properties(emacs, additional_properties.into_iter())?.apply(
+        &mut child_status,
+        &mut this_status,
+        &mut message,
+    );
+
     compare_children(
         source,
         emacs,

src/compare/util.rs

@@ -1,5 +1,6 @@
 use std::str::FromStr;
 
+use super::compare_field::ComparePropertiesResult;
 use super::diff::DiffEntry;
 use super::diff::DiffStatus;
 use super::elisp_fact::GetElispFact;
@@ -311,3 +312,28 @@ pub(crate) fn assert_no_children<'b, 's>(
     }
     Ok(())
 }
+
+pub(crate) fn compare_additional_properties<'b, 's, RK, RV, RI>(
+    emacs: &'b Token<'s>,
+    rust_children: RI,
+) -> Result<ComparePropertiesResult<'b, 's>, Box<dyn std::error::Error>>
+where
+    RK: AsRef<str>,
+    RV: AsRef<str>,
+    RI: Iterator<Item = (RK, RV)> + ExactSizeIterator,
+{
+    for (rust_key, rust_value) in rust_children {
+        let rust_key = rust_key.as_ref();
+        let rust_value = rust_value.as_ref();
+        let emacs_value = get_property_quoted_string(emacs, rust_key)?;
+        if Some(rust_value) != emacs_value.as_ref().map(String::as_str) {
+            let this_status = DiffStatus::Bad;
+            let message = Some(format!(
+                "{} mismatch (emacs != rust) {:?} != {:?}",
+                rust_key, emacs_value, rust_value
+            ));
+            return Ok(ComparePropertiesResult::SelfChange(this_status, message));
+        }
+    }
+    Ok(ComparePropertiesResult::NoChange)
+}