[WIP] Changes to build fuchsia integration_flutter_test/embedder

This is a work in progress, with changes that successfully
compile the embedder test.

This commit leverages new build rules, added in PR flutter#27996,
that enable building flutter tests as Fuchsia components, and
dependencies on Dart libraries from the Fuchsia SDK (Fuchsia Dart APIs
and Dart FIDL bindings).

Notable:

* Adds dart third_party library "quiver" version 2.1.5 to support a
  dependency from a Fuchsia Dart library required by the integration
  test.
* Leverages the recent addition of TestWithEnvironment to the Fuchsia
  SDK, and blends this class with Googletest's (gtest) `testing::Test`,
  from Flutter's pre-existing gtest (third_party dependency).

DEPS

@@ -444,6 +444,9 @@ deps = {
   'src/third_party/pkg/process_runner':
   Var('github_git') + '/google/process_runner.git' + '@' + 'd632ea0bfd814d779fcc53a361ed33eaf3620a0b', # 4.0.1
 
+  'src/third_party/pkg/quiver':
+  Var('github_git') + '/google/quiver-dart.git' + '@' + '66f473cca1332496e34a783ba4527b04388fd561', # 2.1.5
+
   'src/third_party/pkg/vector_math':
   Var('github_git') + '/google/vector_math.dart.git' + '@' + 'v2.1.0',
 

shell/platform/fuchsia/flutter/BUILD.gn

@@ -813,5 +813,6 @@ group("tests") {
     ":testing_tests",
     ":txt_tests",
     ":ui_tests",
+    "integration_flutter_tests",
   ]
 }

shell/platform/fuchsia/flutter/integration_flutter_tests/BUILD.gn

@@ -0,0 +1,9 @@
+# Copyright 2013 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.
+
+group("integration_flutter_tests") {
+  testonly = true
+
+  deps = [ "embedder:tests" ]
+}

shell/platform/fuchsia/flutter/integration_flutter_tests/OWNERS

@@ -0,0 +1,5 @@
+dworsham@google.com
+sanjayc@google.com
+richkadel@google.com
+
+# COMPONENT: FlutteronFuchsia

shell/platform/fuchsia/flutter/integration_flutter_tests/embedder/BUILD.gn

@@ -0,0 +1,73 @@
+# Copyright 2013 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.
+
+assert(is_fuchsia)
+
+import("//build/fuchsia/sdk.gni")
+import("//flutter/tools/fuchsia/fuchsia_archive.gni")
+
+group("tests") {
+  testonly = true
+  deps = [
+    ":flutter_scenic_embedder_test",
+    "//flutter/shell/platform/fuchsia/flutter/integration_flutter_tests/embedder/child-view",
+    "//flutter/shell/platform/fuchsia/flutter/integration_flutter_tests/embedder/parent-view",
+  ]
+}
+
+executable("flutter_scenic_embedder_test_bin") {
+  testonly = true
+
+  output_name = "flutter_scenic_embedder_test"
+
+  sources = [
+    "flutter-scenic-embedder-test.cc",
+    "flutter-scenic-embedder-test.h",
+  ]
+
+  # This is needed for //third_party/googletest for linking zircon symbols.
+  libs = [ "$fuchsia_sdk_path/arch/$target_cpu/sysroot/lib/libzircon.so" ]
+
+  include_dirs = [ "//flutter/shell/platform/fuchsia/flutter/integration_flutter_tests/fuchsia_testing" ]
+
+  public_deps = [ "//third_party/googletest:gtest" ]
+
+  # The use of these dependencies is temporary and will be moved behind the
+  # embedder API.
+  flutter_deps = [
+    "//flutter/lib/ui",
+    "//third_party/dart/runtime:libdart_jit",
+    "//third_party/dart/runtime/platform:libdart_platform_jit",
+  ]
+
+  deps = [
+           "$fuchsia_sdk_root/fidl:fuchsia.sys",
+           "$fuchsia_sdk_root/fidl:fuchsia.ui.app",
+           "$fuchsia_sdk_root/fidl:fuchsia.ui.input",
+           "$fuchsia_sdk_root/fidl:fuchsia.ui.policy",
+           "$fuchsia_sdk_root/fidl:fuchsia.ui.scenic",
+           "$fuchsia_sdk_root/pkg:fit",
+           "$fuchsia_sdk_root/pkg:sys_cpp",
+           "$fuchsia_sdk_root/pkg:sys_cpp_testing",
+           "//flutter/shell/platform/fuchsia/flutter/integration_flutter_tests/fuchsia_testing/src/lib/ui/base_view",
+           "$fuchsia_sdk_root/pkg:scenic_cpp",
+           "//third_party/googletest:gtest_main",
+           "//flutter/shell/platform/fuchsia/flutter/integration_flutter_tests/fuchsia_testing/src/ui/testing/views",
+           "$fuchsia_sdk_root/pkg:zx",
+           "$fuchsia_sdk_root/pkg:async-loop-cpp",
+           "$fuchsia_sdk_root/pkg:async-loop-default",
+         ] + flutter_deps
+}
+
+fuchsia_test_archive("flutter_scenic_embedder_test") {
+  deps = [
+    ":flutter_scenic_embedder_test_bin",
+    "//flutter/shell/platform/fuchsia/flutter/integration_flutter_tests/embedder/child-view",
+    "//flutter/shell/platform/fuchsia/flutter/integration_flutter_tests/embedder/parent-view",
+  ]
+
+  binary = "$target_name"
+
+  cmx_file = rebase_path("meta/$target_name.cmx")
+}

shell/platform/fuchsia/flutter/integration_flutter_tests/embedder/README.md

@@ -0,0 +1,144 @@
+# `flutter scenic embedder tests`
+
+To run the tests:
+
+## Sync your fuchsia.git checkout to your current Fuchsia SDK version
+
+First, sync your Fuchsia checkout and dependencies to match the versions used
+to generate the Fuchsia SDK version you are using in the flutter/engine repo.
+Typically, you've used `gclient sync` to download the version specified in the
+flutter/engine `DEPS` file.
+
+In a web browser, open
+https://chrome-infra-packages.appspot.com/p/fuchsia/sdk/core, select your
+architecture, click one of the "Instances" to open it's detail page, and then
+edit the web URL to replace the selected instance ID with the instance ID you
+synched with, from the DEPS file (for the same architecture).
+
+From the new page matching your current instance ID, copy the `jiri_snapshot`
+(only the value after the colon) and set a shell variable to this value:
+
+```shell
+$ JIRI_SNAPSHOT="<tag>" # for example, 6.20210809.3.1
+```
+
+Now, from your `$FUCHSIA_DIR` directory, do the following:
+
+Use `git` to checkout the version of the `$FUCHSIA_DIR/integration` directory
+matching your Fuchsia SDK's `$JIRI_SNAPSHOT`.
+
+### Option 1: Checkout the matching tagged revision of Fuchsia, if available
+
+Depending on your fuchsia.git configuration, you may be able to check it out by
+tag:
+
+```shell
+$ cd "$FUCHSIA_DIR"
+$ git -C integration checkout "tags/releases/$JIRI_SNAPSHOT"
+```
+
+### Option 2: Use git to find the matching revision of Fuchsia
+
+But if your `$FUCHSIA_DIR/integration` git checkout doesn't have the release
+tags, you may be able to find the right version by searching its git log
+history:
+
+```shell
+$ cd "$FUCHSIA_DIR"
+$ git -C integration log --grep="Roll sdk-core packages to version:$JIRI_SNAPSHOT"
+commit abcdef1234567890abcdef123456789
+Author: global-integration-roller ...
+Date: ...
+
+    [roll] Roll sdk-core packages to version:6.20210809.4.1
+...
+```
+
+***IMPORANT: Your search may return more than one result. If so, choose one. Or
+you may get no result (perhaps due to a manual roll, or other maintenance
+activity). In this case, you may need to modify the `git log` `--grep=` pattern
+and drop suffixes from your `$JIRI_SNAPSHOT` version to find a closely related
+version. This would not guarantee compatibility, so if you're not a gambler, you
+may want to update the SDK instance ID in your local `DEPS` file, and re-run
+`gclient sync`, to ensure your installed `$FUCHSIA_SDK` matches the version
+returned by `git log`.***
+
+### Update fuchsia.git to match `integration`, and sync all dependencies
+
+```shell
+$ cd "$FUCHSIA_DIR"
+$ git checkout "$(sed -ne 's/ *revision="\([^"]*\).*/\1/p' $(find integration -name stem) )"
+$ fx sync-from-stem  # this will be very slow the first time, while it caches git history
+```
+
+The `fx sync-from-stem` command uses `jiri` to update all dependencies (other
+`git` repos and CIPD prebuilts) to match the current $FUCHSIA_DIR commit (as set
+by `git checkout ...` above). These versions should match the versions used when
+creating the Fuchsia SDK you are using.
+
+If you are also modifying Fuchsia, you may want to cherry-pick your changes on
+top of your current checkout.
+
+## Beware of Dart SDK differences between Flutter and Fuchsia
+
+NOTE: These steps may or may not be necessary, and have not been confirmed
+at this point.
+
+To match Fuchsia's version of Dart, you may be able to update your DEPS file to
+install a version of the Dart SDK that matches the version used in your
+revision-synched `$FUCHSIA_DIR` prebuilts.
+
+```shell
+$ cat "$FUCHSIA_DIR/prebuilt/third_party/dart/linux-x64/version"
+2.14.0-289.0.dev # for example
+```
+
+https://dart.googlesource.com/sdk/+/refs/tags/<the version tag from above>
+
+You may be able to use the `tag` reference hash, to update the Dart SDK
+dependency in `DEPS`, use `gclient sync` to download that version, and then
+run `create_updated_flutter_deps.py` to update DEPS once more with the correct
+versions of other dependencies required by the newly updated version of the
+Dart SDK.
+
+```shell
+$ cd "$FLUTTER_ENGINE_DIR/src"
+$ gclient sync
+$ tools/dart/create_updated_flutter_deps.py
+$ gclient sync
+```
+
+## Build flutter/engine:
+
+```shell
+$ cd "$FLUTTER_ENGINE_DIR/src"
+$ ./flutter/tools/gn --fuchsia <flags> \
+      # for example: --goma --fuchsia-cpu=x64 --runtime-mode=release
+$ ninja -C out/fuchsia_release_x64
+```
+
+## If needed, replace Fuchsia's flutter_runner with your custom built runner
+
+Follow the steps in the Flutter wiki, under
+[Compiling for Fuchsia](https://github.com/flutter/flutter/wiki/Compiling-the-engine#compiling-for-fuchsia),
+including the subsection titled
+[Deploy to Fuchsia](https://github.com/flutter/flutter/wiki/Compiling-the-engine#deploy-to-fuchsia).
+
+## Build and reboot your Fuchsia device, for example:
+
+```shell
+$ cd "$FUCHSIA_DIR"
+$ # you may want to run `fx clean`, particularly right after `fx sync-from-stem`
+$ fx set core.<board> --with //bundles:tests --with-base //topaz/bundles:buildbot
+$ fx build
+$ fx reboot -r
+
+$ fx pm publish -a -repo "$(cat ~/fuchsia/.fx-build-dir)/amber-files/" \
+    -f "$FLUTTER_ENGINE_DIR"/src/out/fuchsia_*64/flutter_scenic_embedder_test-0.far
+
+$ fx shell run-test-component \
+    fuchsia-pkg://fuchsia.com/flutter_scenic_embedder_test#meta/flutter_scenic_embedder_test.cmx
+```
+
+The embedder tests must be run on a product without a graphical base shell,
+such as `core` because it starts and stops Scenic.

shell/platform/fuchsia/flutter/integration_flutter_tests/embedder/child-view/BUILD.gn

@@ -0,0 +1,20 @@
+# Copyright 2013 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("//build/fuchsia/sdk.gni")
+import("//flutter/tools/fuchsia/dart/dart_library.gni")
+import("//flutter/tools/fuchsia/flutter/flutter_component.gni")
+
+dart_library("lib") {
+  package_name = "child-view"
+  sources = [ "main.dart" ]
+
+  deps = []
+}
+
+flutter_component("child-view") {
+  manifest = "meta/child_view.cmx"
+  main_package = "child-view"
+  deps = [ ":lib" ]
+}

shell/platform/fuchsia/flutter/integration_flutter_tests/embedder/child-view/lib/main.dart

@@ -0,0 +1,35 @@
+// Copyright 2013 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:async';
+// import 'package:flutter/material.dart';
+
+void main(List<String> args) async {
+  // final app = MaterialApp(home: TestApp(), debugShowCheckedModeBanner: false);
+  // runApp(app);
+}
+
+// See https://medium.com/icnh/flutter-without-flutter-15177c91d066
+// Reacting to Touch Event
+
+// class TestApp extends StatelessWidget {
+//   static const _yellow = Color.fromARGB(255, 255, 255, 0);
+//   static const _pink = Color.fromARGB(255, 255, 0, 255);
+
+//   final _backgroundColor = ValueNotifier(_pink);
+
+//   @override
+//   Widget build(BuildContext context) {
+//     return Listener(
+//       onPointerDown: (_) => _backgroundColor.value = _yellow,
+//       child: AnimatedBuilder(
+//           animation: _backgroundColor,
+//           builder: (context, _) {
+//             return Container(
+//               color: _backgroundColor.value,
+//             );
+//           }),
+//     );
+//   }
+// }

shell/platform/fuchsia/flutter/integration_flutter_tests/embedder/child-view/meta/child_view.cmx

@@ -0,0 +1,13 @@
+{
+    "program": {
+        "data": "data/child_view"
+    },
+    "sandbox": {
+        "services": [
+            "fuchsia.fonts.Provider",
+            "fuchsia.sys.Environment",
+            "fuchsia.ui.input.ImeService",
+            "fuchsia.ui.scenic.Scenic"
+        ]
+    }
+}

shell/platform/fuchsia/flutter/integration_flutter_tests/embedder/child-view/pubspec.yaml

@@ -0,0 +1,8 @@
+# Copyright 2013 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.
+
+name: child_view
+
+environment:
+  sdk: '>=2.12.0 <3.0.0'