Flutter

A Flutter app draws everything itself, into a canvas on the web and into its own view on macOS and iOS. There are no HTML elements or native controls to read. What Flutter does publish is its semantics tree: the description of the screen it gives screen readers. facetshot reads that tree, so checks, steps and session refs are meant to work on a Flutter app the same way they work elsewhere, with no Flutter-specific setup in your app. So far this has been tried on the web; see Status for macOS and iOS.

Each platform goes through the path facetshot already has for it:

Flutter build	Taken as	Guide
web	a web page (/path targets)	Web apps
macOS	a native Mac app (app:/path on mac)	Desktop apps
iOS	an app on the simulator (app:/path on iphone, ipad-…)	iOS simulators

examples/flutter is a small app set up for the web and macOS.

On the web

Flutter’s web build is a folder of static files, so facetshot can serve it itself. No server command is needed:

web: {
  build: {
    cmd: 'flutter build web --release',
    inputs: ['lib', 'web', 'pubspec.yaml'],
    output: 'build/web'
  }
}

When a page turns out to be a Flutter app, facetshot does two things before it counts the page as ready:

• It turns on the semantics tree. Flutter leaves it off until a screen reader asks for it, through a hidden “enable accessibility” button; facetshot presses that button.
• It waits until Flutter has drawn its first frame, which is when the tree appears.

After that, check reads the tree (an element running off the screen shows up as an overflow or clipped finding), and a session lists the app’s buttons and fields with refs. Flutter describes some widgets differently from HTML: the items of a popup menu, for example, are listed as buttons.

To use paths such as /settings, give your app path-based URLs (usePathUrlStrategy() from flutter_web_plugins); facetshot’s server answers every path with index.html.

On macOS

The macOS build is a native Mac app:

desktop: {
  kind: 'macos',
  build: {
    cmd: 'flutter build macos --release',
    inputs: ['lib', 'macos', 'pubspec.yaml'],
    output: 'build/macos/Build/Products/Release/my_app.app',
    heavy: true
  }
}

facetshot launches the app for each screen and tells it what to show through environment variables (FACETSHOT_ROUTE, FACETSHOT_APPEARANCE, and the rest listed under Native Mac apps). A few lines in main() can follow them, as the example does:

final route = kIsWeb ? null : Platform.environment['FACETSHOT_ROUTE'];
runApp(MyApp(initialRoute: route ?? '/'));

Steps and sessions use macOS’s Accessibility interface, which Flutter’s macOS embedder answers from its semantics tree. They need the Accessibility permission (Permissions). What the app prints with print or debugPrint is in the logs.

Some Flutter versions can’t build for macOS with a recent Xcode; see Status.

On iOS

Build the app for the simulator (flutter build ios --simulator) and set it up as any iOS app under apple, as iOS simulators describes. Steps go through XCUITest, which reads the same accessibility information. From a simulator, facetshot reads the app’s lines in the system log (Logs).