Compare plain list item counter.

src/compare/diff.rs

@@ -52,6 +52,7 @@ use crate::types::Paragraph;
 use crate::types::PlainLink;
 use crate::types::PlainList;
 use crate::types::PlainListItem;
+use crate::types::PlainListItemCounter;
 use crate::types::PlainListType;
 use crate::types::PlainText;
 use crate::types::Planning;
@@ -754,6 +755,7 @@ fn compare_plain_list<'s>(
     let mut this_status = DiffStatus::Good;
     let mut message = None;
 
+    // Compare type
     // :type is an unquoted atom of either descriptive, ordered, or unordered
     let list_type = get_property_unquoted_atom(emacs, ":type")?;
     match (list_type, &rust.list_type) {
@@ -831,17 +833,41 @@ fn compare_plain_list_item<'s>(
         .collect::<Result<Vec<_>, _>>()?;
     child_status.push(artificial_diff_scope("contents", contents_status)?);
 
-    // TODO: Compare :counter :pre-blank
+    // Compare bullet
     let bullet = get_property_quoted_string(emacs, ":bullet")?
         .ok_or("Plain list items must have a :bullet.")?;
     if bullet != rust.bullet {
         this_status = DiffStatus::Bad;
         message = Some(format!(
-            "Plain list item bullet mismatch (emacs != rust) {:?} != {:?}",
+            "Bullet mismatch (emacs != rust) {:?} != {:?}",
             bullet, rust.bullet
         ));
     }
 
+    // Compare counter
+    let counter = get_property_unquoted_atom(emacs, ":counter")?;
+    let counter: Option<PlainListItemCounter> = counter
+        .map(|val| val.parse())
+        .map_or(Ok(None), |r| r.map(Some))?;
+    match (counter, rust.counter) {
+        (None, None) => {}
+        (None, Some(_)) | (Some(_), None) => {
+            this_status = DiffStatus::Bad;
+            message = Some(format!(
+                "Counter mismatch (emacs != rust) {:?} != {:?}",
+                counter, rust.counter
+            ));
+        }
+        (Some(e), Some(r)) if e != r => {
+            this_status = DiffStatus::Bad;
+            message = Some(format!(
+                "Counter mismatch (emacs != rust) {:?} != {:?}",
+                counter, rust.counter
+            ));
+        }
+        (Some(_), Some(_)) => {}
+    };
+
     // Compare checkbox
     let checkbox = get_property(emacs, ":checkbox")?
         .map(Token::as_atom)
@@ -861,6 +887,8 @@ fn compare_plain_list_item<'s>(
         }
     };
 
+    // TODO: Compare :pre-blank
+
     Ok(DiffResult {
         status: this_status,
         name: rust.get_elisp_name(),