Add a test of an Android platform view that draws a gradient (#153878)

Closes https://github.com/flutter/flutter/issues/152376.

The gradient, for posterity, looks like this:

<img src="https://github.com/user-attachments/assets/bed9599a-4e16-499c-af79-b51980095e89" width="150">

Let's see if CI agrees!

/cc @johnmccutchan

dev/bots/suite_runners/run_flutter_driver_android_tests.dart

@@ -44,6 +44,27 @@ Future<void> runFlutterDriverAndroidTests() async {
     'flutter',
     <String>[
       'drive',
+      'lib/blue_rectangle_main.dart',
+      // There are no reason to enable development flags for this test.
+      // Disable them to work around flakiness issues, and in general just
+      // make less things start up unnecessarily.
+      '--no-dds',
+      '--no-enable-dart-profiling',
+      '--test-arguments=test',
+      '--test-arguments=--reporter=expanded',
+    ],
+    workingDirectory: path.join(
+      'dev',
+      'integration_tests',
+      'android_driver_test',
+    ),
+  );
+
+  await runCommand(
+    'flutter',
+    <String>[
+      'drive',
+      'lib/blue_orange_gradient_platform_view_main.dart',
       // There are no reason to enable development flags for this test.
       // Disable them to work around flakiness issues, and in general just
       // make less things start up unnecessarily.

dev/integration_tests/android_driver_test/android/app/src/main/kotlin/com/example/android_driver_test/BlueOrangeGradientPlatformViewFactory.kt

@@ -0,0 +1,72 @@
+// Copyright 2014 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+@file:Suppress("PackageName")
+
+package com.example.android_driver_test
+
+import android.content.Context
+import android.graphics.Canvas
+import android.graphics.Color
+import android.graphics.LinearGradient
+import android.graphics.Paint
+import android.graphics.Shader
+import android.view.View
+import android.view.ViewGroup
+import io.flutter.plugin.platform.PlatformView
+import io.flutter.plugin.platform.PlatformViewFactory
+
+class BlueOrangeGradientPlatformViewFactory : PlatformViewFactory(null) {
+    override fun create(
+        context: Context,
+        viewId: Int,
+        args: Any?
+    ): PlatformView = GradientPlatformView(context)
+}
+
+private class GradientPlatformView(
+    context: Context
+) : View(context),
+    PlatformView {
+    val paint = Paint()
+
+    init {
+        layoutParams =
+            ViewGroup.LayoutParams(
+                ViewGroup.LayoutParams.MATCH_PARENT,
+                ViewGroup.LayoutParams.MATCH_PARENT
+            )
+    }
+
+    override fun getView(): View = this
+
+    override fun dispose() {}
+
+    override fun onDraw(canvas: Canvas) {
+        canvas.drawRect(0f, 0f, width.toFloat(), height.toFloat(), paint)
+        super.onDraw(canvas)
+    }
+
+    override fun onSizeChanged(
+        w: Int,
+        h: Int,
+        oldw: Int,
+        oldh: Int
+    ) {
+        paint.shader =
+            LinearGradient(
+                0f,
+                0f,
+                w.toFloat(),
+                h.toFloat(),
+                intArrayOf(
+                    Color.rgb(0x41, 0x69, 0xE1),
+                    Color.rgb(0xFF, 0xA5, 0x00)
+                ),
+                null,
+                Shader.TileMode.CLAMP
+            )
+        super.onSizeChanged(w, h, oldw, oldh)
+    }
+}

dev/integration_tests/android_driver_test/android/app/src/main/kotlin/com/example/android_driver_test/MainActivity.kt

@@ -11,8 +11,18 @@ import androidx.core.view.WindowCompat
 import androidx.core.view.WindowInsetsCompat
 import androidx.core.view.WindowInsetsControllerCompat
 import io.flutter.embedding.android.FlutterActivity
+import io.flutter.embedding.engine.FlutterEngine
 
 class MainActivity : FlutterActivity() {
+    override fun configureFlutterEngine(flutterEngine: FlutterEngine) {
+        // Intentionally do not use GeneratedPluginRegistrant.
+
+        flutterEngine
+            .platformViewsController
+            .registry
+            .registerViewFactory("blue_orange_gradient_platform_view", BlueOrangeGradientPlatformViewFactory())
+    }
+
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
 

dev/integration_tests/android_driver_test/lib/blue_orange_gradient_platform_view_main.dart

@@ -0,0 +1,31 @@
+// Copyright 2014 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'dart:io' as io;
+
+import 'package:flutter/foundation.dart';
+import 'package:flutter/material.dart';
+import 'package:flutter_driver/driver_extension.dart';
+
+void main() {
+  enableFlutterDriverExtension();
+
+  if (kIsWeb || !io.Platform.isAndroid) {
+    throw UnsupportedError('This app should only run on Android devices.');
+  }
+
+  runApp(const MainApp());
+}
+
+final class MainApp extends StatelessWidget {
+  const MainApp({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return const MaterialApp(
+      debugShowCheckedModeBanner: false,
+      home: AndroidView(viewType: 'blue_orange_gradient_platform_view'),
+    );
+  }
+}

dev/integration_tests/android_driver_test/test_driver/blue_orange_gradient_platform_view_main_test.dart

@@ -0,0 +1,47 @@
+// Copyright 2014 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter_driver/flutter_driver.dart';
+import 'package:flutter_driver/src/native_driver.dart';
+import 'package:test/test.dart';
+
+import '_flutter_goldens_fork.dart';
+
+// TODO(matanlurey): This is done automatically by 'flutter test' but not by
+// 'flutter drive'. If we get closer to shipping the native 'flutter drive'
+// command, we should look into if 'flutter_test_config.dart', or a similar
+// mechanism, can be used to configure this automatically.
+void main() async {
+  await testExecutable(_main);
+}
+
+Future<void> _main() async {
+  // To generate golden files locally, uncomment the following line.
+  // autoUpdateGoldenFiles = true;
+
+  late FlutterDriver flutterDriver;
+  late NativeDriver nativeDriver;
+
+  setUpAll(() async {
+    flutterDriver = await FlutterDriver.connect();
+    nativeDriver = await AndroidNativeDriver.connect();
+  });
+
+  tearDownAll(() async {
+    await nativeDriver.close();
+    await flutterDriver.close();
+  });
+
+  test(
+    'should screenshot and match a blue (top left) -> orange (bottom right) gradient',
+    () async {
+      await flutterDriver.waitFor(find.byType('AndroidView'));
+      await expectLater(
+        nativeDriver.screenshot(),
+        matchesGoldenFile('android_driver_test.BlueOrangeGradient.png'),
+      );
+    },
+    timeout: Timeout.none,
+  );
+}

dev/integration_tests/android_driver_test/test_driver/blue_rectangle_main_test.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:io' as io;
-
 import 'package:flutter_driver/flutter_driver.dart';
 import 'package:flutter_driver/src/native_driver.dart';
 import 'package:test/test.dart';
@@ -18,34 +16,27 @@ void main() async {
   await testExecutable(_main);
 }
 
-final bool _isLuciCi = io.Platform.environment['LUCI_CI'] == 'True';
-
 Future<void> _main() async {
   // To generate golden files locally, uncomment the following line.
   // autoUpdateGoldenFiles = true;
 
-  FlutterDriver? flutterDriver;
-  NativeDriver? nativeDriver;
+  late FlutterDriver flutterDriver;
+  late NativeDriver nativeDriver;
 
   setUpAll(() async {
-    flutterDriver = await FlutterDriver.connect(
-      // TODO(matanlurey): Workaround log uploading in LUCI not being enabled.
-      // Default to true on CI because log uploading doesn't work.
-      // See <https://github.com/flutter/flutter/issues/152775>.
-      printCommunication: _isLuciCi,
-    );
+    flutterDriver = await FlutterDriver.connect();
     nativeDriver = await AndroidNativeDriver.connect();
   });
 
   tearDownAll(() async {
-    await nativeDriver?.close();
-    await flutterDriver?.close();
+    await nativeDriver.close();
+    await flutterDriver.close();
   });
 
   test('should screenshot and match a full-screen blue rectangle', () async {
-    await flutterDriver?.waitFor(find.byType('DecoratedBox'));
+    await flutterDriver.waitFor(find.byType('DecoratedBox'));
     await expectLater(
-      nativeDriver?.screenshot(),
+      nativeDriver.screenshot(),
       matchesGoldenFile('android_driver_test.BlueRectangle.png'),
     );
   }, timeout: Timeout.none);

packages/flutter_driver/lib/src/native/goldens.dart

@@ -124,7 +124,7 @@ final class NaiveLocalFileComparator with GoldenFileComparator {
     try {
       goldenBytes = await goldenFile.readAsBytes();
     } on io.PathNotFoundException {
-      throw TestFailure('Golden file not found: $golden');
+      throw TestFailure('Golden file not found: ${goldenFile.path}');
     }
 
     if (goldenBytes.length != imageBytes.length) {