feat(watcher): Enhance change stream watchers with buffering and EventEmitter support; update dependency versions

test/test.watch.ts

@@ -60,6 +60,43 @@ tap.test('should watch a collection', async (toolsArg) => {
   await done.promise;
 });
 
+// ======= New tests for EventEmitter and buffering support =======
+tap.test('should emit change via EventEmitter', async (tools) => {
+  const done = tools.defer();
+  const watcher = await House.watch({});
+  watcher.on('change', async (houseArg) => {
+    // Expect a House instance
+    expect(houseArg).toBeDefined();
+    // Clean up
+    await watcher.stop();
+    done.resolve();
+  });
+  // Trigger an insert to generate a change event
+  const h = new House();
+  await h.save();
+  await done.promise;
+});
+
+tap.test('should buffer change events when bufferTimeMs is set', async (tools) => {
+  const done = tools.defer();
+  // bufferTimeMs collects events into arrays every 50ms
+  const watcher = await House.watch({}, { bufferTimeMs: 50 });
+  let received: House[];
+  watcher.changeSubject.subscribe(async (batch: House[]) => {
+    if (batch && batch.length > 0) {
+      received = batch;
+      await watcher.stop();
+      done.resolve();
+    }
+  });
+  // Rapidly insert multiple docs
+  const docs = [new House(), new House(), new House()];
+  for (const doc of docs) await doc.save();
+  await done.promise;
+  // All inserts should be in one buffered batch
+  expect(received.length).toEqual(docs.length);
+});
+
 // =======================================
 // close the database connection
 // =======================================