Flutter Driver Control & Screenshot

This skill outlines the process of adding flutter_driver support to a Flutter application, launching it via the Dart MCP server, controlling it (tapping, finding widgets), and capturing screenshots (handling Web/Desktop specific constraints).

Prerequisites

1. Dart MCP Server: Ensure the dart-mcp-server is active.
2. Flutter Project: You need a working Flutter project.

Step 1: Add Dependency

Add flutter_driver to the dev_dependencies in your pubspec.yaml.

dev_dependencies:
  flutter_driver:
    sdk: flutter

Run dart pub get or use the mcp_dart-mcp-server_pub tool.

Step 2: Create Driver Entry Point

Create a separate entry point, typically test_driver/app.dart, to enable the driver extension without polluting main.dart.

[!IMPORTANT] Replace your_app_package_name with the actual name of your package as defined in pubspec.yaml.

// test_driver/app.dart
import 'package:flutter_driver/driver_extension.dart';
import 'package:your_app_package_name/main.dart' as app; // Import your main app

void main() {
  // Enable the extension
  enableFlutterDriverExtension();

  // Run the app
  app.main();
}

Step 3: Launch App via MCP

Use the mcp_dart-mcp-server_launch_app tool.

• target: test_driver/app.dart
• device: chrome (or macos, linux, windows)
• root: Absolute path to your project root.

Note: The tool returns a DTD URI (Data Tooling Daemon) and a PID. Save these.

Step 4: Connect to DTD

Use mcp_dart-mcp-server_connect_dart_tooling_daemon with the URI returned from the launch step.

{
  "uri": "ws://127.0.0.1:..."
}

Step 5: Web Screenshot Strategy (Browser Subagent)

If running on Web (Chrome), flutter_driver’s screenshot command may not work or may not be supported directly in all environments. A robust fallback is to use the browser_subagent.

1. Get App URL: Use mcp_dart-mcp-server_get_app_logs with the app’s PID. Look for lines like A Dart VM Service on Chrome is available at: http://127.0.0.1:XXXXX. The app logs usually contain the local HTTP URL.
2. Navigate & Snapshot: Call browser_subagent.
   • Task: “Navigate to [URL]. Wait for render. Take a screenshot.”

Step 6: Control the App (Flutter Driver)

Use mcp_dart-mcp-server_flutter_driver to interact with the app.

• Get Widget Tree: mcp_dart-mcp-server_get_widget_tree (useful to find keys/labels).
• Tap:

  {
    "command": "tap",
    "finderType": "ByText",
    "text": "Settings"
  }
  

• Scroll, Enter Text, etc. are also available.

Step 7: Cleanup

Always stop the app when done to free up ports and resources.

• Use mcp_dart-mcp-server_stop_app with the PID.

Example Workflow

1. Launch test_driver/app.dart.
2. Connect DTD.
3. Log Check: Find localhost URL.
4. Browser Subagent: Navigate & Screenshot (Home/Dashboard).
5. Flutter Driver: Tap “Tasks” tab.
6. Browser Subagent: Screenshot (Tasks).
7. Flutter Driver: Tap “Settings” tab.
8. Browser Subagent: Screenshot (Settings).
9. Stop App.