Fix text not serializing correctly when having utf8 boundries

Author: bnchi

mdast_util_to_markdown/src/state.rs

@@ -242,7 +242,9 @@ impl<'a> State<'a> {
                     results.push(' ');
                     new_info.before = " ";
                 } else {
-                    new_info.before = &results[results.len() - 1..];
+                    if let Some(last_char) = results.chars().last() {
+                        new_info.before = &results[results.len() - last_char.len_utf8()..];
+                    }
                 }
             }
 

mdast_util_to_markdown/tests/roundtrip.rs

@@ -398,6 +398,15 @@ a _\\__ is this emphasis? _\\__"
     .unwrap())
     .unwrap();
     assert_eq!(to(&from(&doc, &Default::default()).unwrap()).unwrap(), doc);
+
+    let doc = "𝄞[some](another)";
+    let tree = markdown::to_mdast(&doc, &markdown::ParseOptions::default()).unwrap();
+
+    assert_eq!(
+        to(&tree).unwrap(),
+        "𝄞[some](another)\n",
+        "should support utf8 in boundries when serializing"
+    );
 }
 
 fn remove_pos(node: &mut Node) {