fix test

add a simple example

doc/gui/examples/async_callback.py

@@ -0,0 +1,52 @@
+# Copyright 2021-2024 Avaiga Private Limited
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with
+# the License. You may obtain a copy of the License at
+#
+#        http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on
+# an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
+# specific language governing permissions and limitations under the License.
+# -----------------------------------------------------------------------------------------
+# To execute this script, make sure that the taipy-gui package is installed in your
+# Python environment and run:
+#     python <script>
+# -----------------------------------------------------------------------------------------
+# Demonstrate how to update the value of a variable across multiple clients.
+# This application creates a thread that sets a variable to the current time.
+# The value is updated for every client when Gui.broadcast_change() is invoked.
+# -----------------------------------------------------------------------------------------
+import asyncio
+
+import taipy.gui.builder as tgb
+from taipy.gui import Gui, State
+
+
+# This callback is invoked inside a separate thread
+# it can access the state but cannot return a value
+async def heavy_function(state: State):
+    state.logs = "Starting...\n"
+    state.logs += "Searching documents\n"
+    await asyncio.sleep(5)
+    state.logs += "Responding to user\n"
+    await asyncio.sleep(5)
+    state.logs += "Fact Checking\n"
+    await asyncio.sleep(5)
+    state.result = "Done!"
+
+logs = ""
+result = "No response yet"
+
+with tgb.Page() as main_page:
+    # the async callback is used as any other callback
+    tgb.button("Respond", on_action=heavy_function)
+    with tgb.part("card"):
+        tgb.text("{logs}", mode="pre")
+
+    tgb.text("# Result", mode="md")
+    tgb.text("{result}")
+
+
+if __name__ == "__main__":
+    Gui(main_page).run(title="Async - Callback")

tests/gui/gui_specific/test_state.py

@@ -54,6 +54,7 @@ def test_state(gui: Gui):
         assert state._get_placeholder_attrs() == (
             "_taipy_p1",
             "_current_context",
+            "__state_id"
         )
 
         assert get_a(state) == 20