1 files changed, 35 insertions, 0 deletions
diff --git a/src/document/changes.rs b/src/document/changes.rs
index faba895..345f151 100644
--- a/src/document/changes.rs
+++ b/src/document/changes.rs
@@ -195,4 +195,39 @@ mod tests {
         assert!(change_from_bytes(bytes, ChangeHash([7; 32])).is_err());
         assert!(change_bytes(&doc, &ChangeHash([7; 32])).is_none());
     }
+
+    /// The authors of the changes after some heads: each node that wrote some, once,
+    /// however their changes were merged; a change without an author is told apart.
+    #[test]
+    fn authors_of_the_changes_since() {
+        use crate::clock::UnixMillis;
+        use crate::document::replica::{Writer, transact};
+        let write = |doc: &mut Document, node: &str, key: &str| {
+            let writer = Writer { node, user: None };
+            transact(doc, UnixMillis(1), &writer, |doc| doc.put(ROOT, key, 1)).unwrap();
+        };
+        let mut base = Document::new();
+        write(&mut base, "node-a", "base");
+        let since = base.get_heads();
+        assert_eq!(authors_since(&base, &since), (Vec::new(), false));
+
+        let mut a = base.fork();
+        write(&mut a, "node-a", "a1");
+        write(&mut a, "node-a", "a2");
+        let mut b = base.fork();
+        write(&mut b, "node-b", "b1");
+        let mut merged = a.clone();
+        merged.merge(&mut b).unwrap();
+        let (mut authors, unknown) = authors_since(&merged, &since);
+        authors.sort();
+        assert_eq!(authors, ["node-a", "node-b"]);
+        assert!(!unknown);
+
+        // A change no node authored (a snapshot's, say).
+        let mut snapshot = Document::new();
+        snapshot.merge(&mut merged.clone()).unwrap();
+        change(&mut snapshot, |doc| doc.put(ROOT, "s", 1).unwrap());
+        let (_, unknown) = authors_since(&snapshot, &merged.get_heads());
+        assert!(unknown);
+    }
 }