test.py

import gradio as gr



def show_warning():
    print("should show: This is a warning message.")
    gr.Warning("This is a warning message.")
    
with gr.Blocks() as demo:

    flash_timer = gr.Timer(
        1,
        active=True,
    )
    flash_timer.tick(
        show_warning,
        inputs=[],
        outputs=[],
    )
    
demo.launch()