Fix ignoring empty update (#111)

* Add test for non-empty update

* Add fix for ignoring empty update

src/doc.rs

@@ -116,7 +116,7 @@ impl Doc {
     pub fn observe(&mut self, py: Python<'_>, f: PyObject) -> PyResult<Py<Subscription>> {
         let sub = self.doc
             .observe_transaction_cleanup(move |txn, event| {
-                if event.before_state != event.after_state {
+                if !event.delete_set.is_empty() || event.before_state != event.after_state {
                     Python::with_gil(|py| {
                         let event = TransactionEvent::new(event, txn);
                         if let Err(err) = f.call1(py, (event,)) {

tests/test_doc.py

@@ -191,3 +191,15 @@ def test_empty_update():
     doc["text"]
     # empty updates should not emit an event
     assert not events
+
+
+def test_not_empty_update():
+    doc = Doc()
+    doc["text"] = text = Text()
+    events = []
+    sub = doc.observe(partial(callback, events))  # noqa: F841
+
+    text += "helloo"
+    events.clear()
+    del text[5]
+    assert events