Add undo manager test

tests/test_pycrdt_yjs.py

@@ -58,3 +58,18 @@ async def test_pycrdt_yjs_1(yws_server, yws_provider, yjs_client):
     await ystate_change.wait()
     assert ycells.to_py() == [{"metadata": {"foo": "bar"}, "source": "1 + 2"}]
     assert ystate.to_py() == {"state": {"dirty": False}}
+
+
+@pytest.mark.parametrize("yjs_client", [2], indirect=True)
+async def test_pycrdt_yjs_2(yws_server, yws_provider, yjs_client):
+    ydoc, _ = yws_provider
+    ydoc["map0"] = map0 = Map()
+    map0_change = watch(map0)
+    await map0_change.wait()
+    assert map0.get("key0") == "val0"
+    # client is synced, let's make a change
+    map0["key1"] = "val1"
+    # wait for client to undo the change
+    map0_change = watch(map0)
+    await map0_change.wait()
+    assert "key1" not in map0

tests/yjs_client_2.js

@@ -0,0 +1,29 @@
+const Y = require('yjs')
+const WebsocketProvider = require('y-websocket').WebsocketProvider
+const ws = require('ws')
+
+const port = process.argv[2]
+const ydoc = new Y.Doc()
+
+const wsProvider = new WebsocketProvider(
+  `ws://127.0.0.1:${port}`, 'my-roomname',
+  ydoc,
+  { WebSocketPolyfill: ws }
+)
+
+wsProvider.on('sync', () => {
+  const map0 = ydoc.getMap('map0')
+  const undoManager = new Y.UndoManager(map0, {
+    trackedOrigins: new Set([wsProvider]),
+  })
+  map0.set('key0', 'val0')
+  undoManager.clear()
+
+  function undo() {
+    undoManager.undo()
+  }
+
+  map0.observe((event, transaction) => {
+    setTimeout(undo, 100)
+  })
+})