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Testing ChatInterface Streaming with Multimodal Messages in gradio-app/gradio

This test suite validates the streaming functionality of Gradio’s ChatInterface component with multimodal message support. It implements a simple echo service that demonstrates progressive text rendering and maintains a global run counter for test verification.

Test Coverage Overview

The test coverage focuses on the ChatInterface’s streaming capabilities and multimodal message handling.

Tests progressive text rendering through character-by-character echo
Verifies multimodal message support
Tracks execution runs using global state
Tests demo launch and unload functionality

Implementation Analysis

The implementation uses a slow_echo function that yields partial message responses to simulate streaming behavior. The approach demonstrates Gradio’s streaming capabilities through generator functions and global state management.

Key patterns include:

Generator-based streaming response
Global run counter for test state
Blocks context for component rendering
Unload handler for test cleanup

Technical Details

Testing tools and configuration:

Gradio ChatInterface with multimodal=True
Blocks API for component organization
Global state management for run tracking
Demo launch configuration for manual testing
Unload handler for test state reset

Best Practices Demonstrated

The test implementation showcases several testing best practices for Gradio applications.

Proper cleanup through unload handlers
Isolation of test state
Progressive response testing
Clear separation of interface setup and testing logic
Modular component configuration

gradio-app/gradio

demo/test_chatinterface_streaming_echo/multimodal_messages_testcase.py

            
import gradio as gr

runs = 0

def reset_runs():
    global runs
    runs = 0

def slow_echo(message, history):
    global runs  # i didn't want to add state or anything to this demo
    runs = runs + 1
    for i in range(len(message['text'])):
        yield f"Run {runs} - You typed: " + message['text'][: i + 1]

chat = gr.ChatInterface(slow_echo, multimodal=True, type="messages")

with gr.Blocks() as demo:
    chat.render()
    # We reset the global variable to minimize flakes
    # this works because CI runs only one test at at time
    # need to use gr.State if we want to parallelize this test
    # currently chatinterface does not support that
    demo.unload(reset_runs)

if __name__ == "__main__":
    demo.launch()