[pkg][vm] Native Assets builder

This package contains the logic for building native assets.

This package is the backend that invokes toplevel `build.dart` scripts.
For more info on these scripts see https://github.com/dart-lang/native.

This is a separate package so that dartdev and flutter_tools can reuse
the same logic without flutter_tools having to import dartdev.

Some design decisions:

* We don't yet have `build_dependencies`, so we use the ordinary
  dependency graph for ordering of native assets builds. (If there is
  a cycle we refuse to run.)
  Bug: https://github.com/dart-lang/pub/issues/3794
* Builds are cached based on all the configuration provided by the
  caller. Environment variables are ignored in caching. This CL also
  contains a unit test that invokes the build by not passing through
  environment variables. However, for Windows we need to pass through
  at least `SYSTEMROOT` for MSVC to run correctly. So we might need
  to further explore if we can/want to lock env variables down.
  Bug: https://github.com/dart-lang/native/issues/32
  Bug: https://github.com/dart-lang/native/issues/33

Run tests:
```
dart tools/generate_package_config.dart && \
tools/test.py -n unittest-asserts-release-linux pkg/native_assets_builder
```

Bug: https://github.com/dart-lang/sdk/issues/50565
Change-Id: I133052d7195373e87d20924d61e1e96e3d34ce8f
Cq-Include-Trybots: luci.dart.try:pkg-linux-debug-try,pkg-linux-release-try,pkg-mac-release-arm64-try,pkg-mac-release-try,pkg-win-release-try
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/300203
Reviewed-by: Liam Appelbe <liama@google.com>
Commit-Queue: Daco Harkes <dacoharkes@google.com>
Reviewed-by: Martin Kustermann <kustermann@google.com>
Reviewed-by: Hossein Yousefi <yousefi@google.com>

.gitignore

@@ -75,6 +75,9 @@ client/tests/drt
 packages
 pubspec.lock
 
+# Files for native assets auto-generated per checkout.
+/.dart_tool/native_assets_builder/
+
 # The top level package file (this is auto-generated per checkout).
 /.dart_tool/package_config.json
 

DEPS

@@ -152,7 +152,7 @@ vars = {
   "matcher_rev": "4dfd9adfdcd3de95e6964fc295075a32635e5b37",
   "mime_rev": "eb9d54b8f6fab9442b2b733e19137dc25fb0b868",
   "mockito_rev": "51a7728927c505a907384860f4a407f8b7219004",
-  "native_rev": "64aa5b500fd71b51a34bf4ef0dc05ec24379be00",
+  "native_rev": "e01aa63e851ce971390bc45fc17d16240b8d164a",
   "package_config_rev": "f41f92cd4d2c539d910f2ef041ba6f6bd8469e78",
   "path_rev": "f8d15c2775835fd61ea5e06bb0ab99232f5ec446",
   "pool_rev": "86b4f4328a32a9e9eb4f1601c8296e22d3e50552",

pkg/front_end/lib/src/api_prototype/experimental_flags_generated.dart

@@ -858,6 +858,9 @@ const AllowedExperimentalFlags defaultAllowedExperimentalFlags =
   "meta": {
     ExperimentalFlag.nonNullable,
   },
+  "native_assets_builder": {
+    ExperimentalFlag.nonNullable,
+  },
   "native_stack_traces": {
     ExperimentalFlag.nonNullable,
   },

pkg/front_end/test/spell_checking_list_common.txt

@@ -204,6 +204,8 @@ asserted
 assertion
 assertions
 asserts
+asset
+assets
 assign
 assignability
 assignable
@@ -3114,6 +3116,7 @@ tokens
 too
 took
 tool
+toolchain
 tools
 top
 topologically

pkg/native_assets_builder/.gitignore

@@ -0,0 +1,48 @@
+# Miscellaneous
+*.class
+*.log
+*.pyc
+*.swp
+.DS_Store
+.atom/
+.buildlog/
+.history
+.svn/
+
+# IntelliJ related
+*.iml
+*.ipr
+*.iws
+.idea/
+
+# The .vscode folder contains launch configuration and tasks you configure in
+# VS Code which you may wish to be included in version control, so this line
+# is commented out by default.
+#.vscode/
+
+# Flutter/Dart/Pub related
+**/doc/api/
+**/ios/Flutter/.last_build_id
+.dart_tool/
+.flutter-plugins
+.flutter-plugins-dependencies
+.packages
+.pub-cache/
+.pub/
+/build/
+
+# Web related
+lib/generated_plugin_registrant.dart
+
+# Symbolication related
+app.*.symbols
+
+# Obfuscation related
+app.*.map.json
+
+# Android Studio will place build artifacts here
+/android/app/debug
+/android/app/profile
+/android/app/release
+
+pubspec.lock

pkg/native_assets_builder/AUTHORS

@@ -0,0 +1,6 @@
+# Below is a list of people and organizations that have contributed
+# to the Dart project. Names should be added to the list like so:
+#
+#   Name/Organization <email address>
+
+Google LLC

pkg/native_assets_builder/LICENSE

@@ -0,0 +1,27 @@
+Copyright 2022, the Dart project authors.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+    * Redistributions of source code must retain the above copyright
+      notice, this list of conditions and the following disclaimer.
+    * Redistributions in binary form must reproduce the above
+      copyright notice, this list of conditions and the following
+      disclaimer in the documentation and/or other materials provided
+      with the distribution.
+    * Neither the name of Google LLC nor the names of its
+      contributors may be used to endorse or promote products derived
+      from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

pkg/native_assets_builder/OWNERS

@@ -0,0 +1 @@
+file:/tools/OWNERS_VM

pkg/native_assets_builder/README.md

@@ -0,0 +1,7 @@
+This package contains the logic for building native assets.
+
+This package is the backend that invokes toplevel `build.dart` scripts.
+For more info on these scripts see https://github.com/dart-lang/native.
+
+This is a separate package so that dartdev and flutter_tools can reuse
+the same logic with flutter_tools having to import dartdev.

pkg/native_assets_builder/analysis_options.yaml

@@ -0,0 +1,27 @@
+include: package:lints/recommended.yaml
+
+analyzer:
+  language:
+    strict-raw-types: true
+    strict-inference: true
+  # The test projects do _not_ have resolved dependencies through
+  # `dart tools/package_deps/bin/package_deps.dart`.
+  # So don't analyze them in the IDE or on the CI.
+  exclude:
+    - test/test_projects/**.dart
+
+linter:
+  rules:
+    - always_declare_return_types
+    - avoid_dynamic_calls
+    - camel_case_types
+    - depend_on_referenced_packages
+    - directives_ordering
+    - prefer_const_declarations
+    - prefer_expression_function_bodies
+    - prefer_final_in_for_each
+    - prefer_final_locals
+    - prefer_relative_imports
+    - prefer_single_quotes
+    - sort_pub_dependencies
+    - unawaited_futures

pkg/native_assets_builder/lib/native_assets_builder.dart

@@ -0,0 +1,6 @@
+// Copyright (c) 2023, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+export 'package:native_assets_builder/src/build_runner/build_runner.dart';
+export 'package:native_assets_builder/src/package_layout/package_layout.dart';

pkg/native_assets_builder/lib/src/build_runner/build_planner.dart

@@ -0,0 +1,102 @@
+// Copyright (c) 2023, the Dart project authors.  Please see the AUTHORS file
+// for details. 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:convert';
+import 'dart:io';
+
+import 'package:kernel/util/graph.dart' as graph;
+import 'package:package_config/package_config.dart';
+
+class NativeAssetsBuildPlanner {
+  final PackageGraph packageGraph;
+  final List<Package> packagesWithNativeAssets;
+  final Uri dartExecutable;
+
+  NativeAssetsBuildPlanner({
+    required this.packageGraph,
+    required this.packagesWithNativeAssets,
+    required this.dartExecutable,
+  });
+
+  static Future<NativeAssetsBuildPlanner> fromRootPackageRoot({
+    required Uri rootPackageRoot,
+    required List<Package> packagesWithNativeAssets,
+    required Uri dartExecutable,
+  }) async {
+    final result = await Process.run(
+      dartExecutable.toFilePath(),
+      [
+        'pub',
+        'deps',
+        '--json',
+      ],
+      workingDirectory: rootPackageRoot.toFilePath(),
+    );
+    final packageGraph = PackageGraph.fromPubDepsJsonString(result.stdout);
+    return NativeAssetsBuildPlanner(
+      packageGraph: packageGraph,
+      packagesWithNativeAssets: packagesWithNativeAssets,
+      dartExecutable: dartExecutable,
+    );
+  }
+
+  List<Package> plan() {
+    final packageMap = {
+      for (final package in packagesWithNativeAssets) package.name: package
+    };
+    final packagesToBuild = packageMap.keys.toSet();
+    final stronglyConnectedComponents = packageGraph.computeStrongComponents();
+    final result = <Package>[];
+    for (final stronglyConnectedComponent in stronglyConnectedComponents) {
+      final stronglyConnectedComponentWithNativeAssets = [
+        for (final packageName in stronglyConnectedComponent)
+          if (packagesToBuild.contains(packageName)) packageName
+      ];
+      if (stronglyConnectedComponentWithNativeAssets.length > 1) {
+        throw Exception(
+          'Cyclic dependency for native asset builds in the following '
+          'packages: $stronglyConnectedComponent.',
+        );
+      } else if (stronglyConnectedComponentWithNativeAssets.length == 1) {
+        result.add(
+            packageMap[stronglyConnectedComponentWithNativeAssets.single]!);
+      }
+    }
+    return result;
+  }
+}
+
+class PackageGraph implements graph.Graph<String> {
+  final Map<String, List<String>> map;
+
+  PackageGraph(this.map);
+
+  /// Construct a graph from the JSON produced by `dart pub deps --json`.
+  factory PackageGraph.fromPubDepsJsonString(String json) =>
+      PackageGraph.fromPubDepsJson(jsonDecode(json) as Map<dynamic, dynamic>);
+
+  /// Construct a graph from the JSON produced by `dart pub deps --json`.
+  factory PackageGraph.fromPubDepsJson(Map<dynamic, dynamic> map) {
+    final result = <String, List<String>>{};
+    final packages = map['packages'] as List<dynamic>;
+    for (final package in packages) {
+      final package_ = package as Map<dynamic, dynamic>;
+      final name = package_['name'] as String;
+      final dependencies = (package_['dependencies'] as List<dynamic>)
+          .whereType<String>()
+          .toList();
+      result[name] = dependencies;
+    }
+    return PackageGraph(result);
+  }
+
+  @override
+  Iterable<String> neighborsOf(String vertex) => map[vertex] ?? [];
+
+  @override
+  Iterable<String> get vertices => map.keys;
+
+  List<List<String>> computeStrongComponents() =>
+      graph.computeStrongComponents(this);
+}

pkg/native_assets_builder/lib/src/build_runner/build_runner.dart

@@ -0,0 +1,220 @@
+// Copyright (c) 2023, the Dart project authors.  Please see the AUTHORS file
+// for details. 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 'dart:io';
+
+import 'package:logging/logging.dart';
+import 'package:native_assets_cli/native_assets_cli.dart';
+
+import '../package_layout/package_layout.dart';
+import '../utils/run_process.dart';
+import 'build_planner.dart';
+
+typedef DependencyMetadata = Map<String, Metadata>;
+
+/// The programmatic API to be used by Dart launchers to invoke native builds.
+///
+/// These methods are invoked by launchers such as dartdev (for `dart run`)
+/// and flutter_tools (for `flutter run` and `flutter build`).
+class NativeAssetsBuildRunner {
+  final Logger logger;
+  final Uri dartExecutable;
+
+  NativeAssetsBuildRunner({
+    required this.logger,
+    required this.dartExecutable,
+  });
+
+  final _metadata = <Target, DependencyMetadata>{};
+
+  /// [workingDirectory] is expected to contain `.dart_tool`.
+  ///
+  /// This method is invoked by launchers such as dartdev (for `dart run`) and
+  /// flutter_tools (for `flutter run` and `flutter build`).
+  ///
+  /// Completes the future with an error if the build fails.
+  Future<List<Asset>> build({
+    required LinkModePreference linkModePreference,
+    required Target target,
+    required Uri workingDirectory,
+    CCompilerConfig? cCompilerConfig,
+    required bool includeParentEnvironment,
+  }) async {
+    assert(_metadata.isEmpty);
+    final packageLayout =
+        await PackageLayout.fromRootPackageRoot(workingDirectory);
+    final packagesWithNativeAssets =
+        await packageLayout.packagesWithNativeAssets;
+    final planner = await NativeAssetsBuildPlanner.fromRootPackageRoot(
+      rootPackageRoot: packageLayout.rootPackageRoot,
+      packagesWithNativeAssets: packagesWithNativeAssets,
+      dartExecutable: Uri.file(Platform.resolvedExecutable),
+    );
+    final plan = planner.plan();
+    final assetList = <Asset>[];
+    for (final package in plan) {
+      final dependencyMetadata = _metadataForPackage(
+        packageGraph: planner.packageGraph,
+        packageName: package.name,
+        targetMetadata: _metadata[target],
+      );
+      final config = await _cliConfig(
+        packageName: package.name,
+        packageRoot: packageLayout.packageRoot(package.name),
+        target: target,
+        linkMode: linkModePreference,
+        buildParentDir: packageLayout.dartToolNativeAssetsBuilder,
+        dependencyMetadata: dependencyMetadata,
+        cCompilerConfig: cCompilerConfig,
+      );
+      final assets = await _buildPackageCached(
+        config,
+        packageLayout.packageConfigUri,
+        workingDirectory,
+        includeParentEnvironment,
+      );
+      assetList.addAll(assets);
+    }
+    return assetList;
+  }
+
+  Future<List<Asset>> _buildPackageCached(
+    BuildConfig config,
+    Uri packageConfigUri,
+    Uri workingDirectory,
+    bool includeParentEnvironment,
+  ) async {
+    final packageName = config.packageName;
+    final outDir = config.outDir;
+    if (!await Directory.fromUri(outDir).exists()) {
+      await Directory.fromUri(outDir).create(recursive: true);
+    }
+
+    final buildOutput = await BuildOutput.readFromFile(outDir: outDir);
+    final lastBuilt = buildOutput?.timestamp.roundDownToSeconds() ??
+        DateTime.fromMillisecondsSinceEpoch(0);
+    final dependencies = buildOutput?.dependencies;
+    final lastChange = await dependencies?.lastModified() ?? DateTime.now();
+
+    if (lastBuilt.isAfter(lastChange)) {
+      logger.info('Skipping build for $packageName in $outDir. '
+          'Last build on $lastBuilt, last input change on $lastChange.');
+      // All build flags go into [outDir]. Therefore we do not have to check
+      // here whether the config is equal.
+
+      setMetadata(config.target, packageName, buildOutput?.metadata);
+      return buildOutput!.assets;
+    }
+
+    return _buildPackage(
+      config,
+      packageConfigUri,
+      workingDirectory,
+      includeParentEnvironment,
+    );
+  }
+
+  Future<List<Asset>> _buildPackage(
+    BuildConfig config,
+    Uri packageConfigUri,
+    Uri workingDirectory,
+    bool includeParentEnvironment,
+  ) async {
+    final outDir = config.outDir;
+    final configFile = outDir.resolve('config.yaml');
+    final buildDotDart = config.packageRoot.resolve('build.dart');
+    final configFileContents = config.toYamlString();
+    logger.info('config.yaml contents: $configFileContents');
+    await File.fromUri(configFile).writeAsString(configFileContents);
+    final buildOutputFile = File.fromUri(outDir.resolve(BuildOutput.fileName));
+    if (await buildOutputFile.exists()) {
+      // Ensure we'll never read outdated build results.
+      await buildOutputFile.delete();
+    }
+    await runProcess(
+      workingDirectory: workingDirectory,
+      executable: dartExecutable.toFilePath(),
+      arguments: [
+        '--packages=${packageConfigUri.toFilePath()}',
+        buildDotDart.toFilePath(),
+        '--config=${configFile.toFilePath()}',
+      ],
+      logger: logger,
+      includeParentEnvironment: includeParentEnvironment,
+    );
+    final buildOutput = await BuildOutput.readFromFile(outDir: outDir);
+    setMetadata(config.target, config.packageName, buildOutput?.metadata);
+    return buildOutput?.assets ?? [];
+  }
+
+  void setMetadata(Target target, String packageName, Metadata? metadata) {
+    if (metadata == null) {
+      return;
+    }
+    _metadata[target] ??= {};
+    _metadata[target]![packageName] = metadata;
+  }
+
+  static Future<BuildConfig> _cliConfig({
+    required String packageName,
+    required Uri packageRoot,
+    required Target target,
+    IOSSdk? targetIOSSdk,
+    required LinkModePreference linkMode,
+    required Uri buildParentDir,
+    CCompilerConfig? cCompilerConfig,
+    DependencyMetadata? dependencyMetadata,
+  }) async {
+    final buildDirName = BuildConfig.checksum(
+      packageRoot: packageRoot,
+      target: target,
+      linkModePreference: linkMode,
+      targetIOSSdk: targetIOSSdk,
+      cCompiler: cCompilerConfig,
+      dependencyMetadata: dependencyMetadata,
+    );
+    final outDirUri = buildParentDir.resolve('$buildDirName/');
+    final outDir = Directory.fromUri(outDirUri);
+    if (!await outDir.exists()) {
+      // TODO(https://dartbug.com/50565): Purge old or unused folders.
+      await outDir.create(recursive: true);
+    }
+    return BuildConfig(
+      outDir: outDirUri,
+      packageRoot: packageRoot,
+      target: target,
+      linkModePreference: linkMode,
+      targetIOSSdk: targetIOSSdk,
+      cCompiler: cCompilerConfig,
+      dependencyMetadata: dependencyMetadata,
+    );
+  }
+
+  DependencyMetadata? _metadataForPackage({
+    required PackageGraph packageGraph,
+    required String packageName,
+    DependencyMetadata? targetMetadata,
+  }) {
+    if (targetMetadata == null) {
+      return null;
+    }
+    final dependencies = packageGraph.neighborsOf(packageName).toSet();
+    return {
+      for (final entry in targetMetadata.entries)
+        if (dependencies.contains(entry.key)) entry.key: entry.value,
+    };
+  }
+}
+
+extension on DateTime {
+  DateTime roundDownToSeconds() =>
+      DateTime.fromMillisecondsSinceEpoch(millisecondsSinceEpoch -
+          millisecondsSinceEpoch % Duration(seconds: 1).inMilliseconds);
+}
+
+extension on BuildConfig {
+  String get packageName =>
+      packageRoot.pathSegments.lastWhere((e) => e.isNotEmpty);
+}

pkg/native_assets_builder/lib/src/package_layout/package_layout.dart

@@ -0,0 +1,94 @@
+// Copyright (c) 2023, the Dart project authors.  Please see the AUTHORS file
+// for details. 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';
+
+import 'package:package_config/package_config.dart';
+
+/// Directory layout for dealing with native assets.
+///
+/// Build scripts for native assets will be run from the context of another
+/// root package.
+///
+/// The directory layout follows pub's convention for caching:
+/// https://dart.dev/tools/pub/package-layout#project-specific-caching-for-tools
+class PackageLayout {
+  /// The root folder of the current dart invocation root package.
+  ///
+  /// `$rootPackageRoot`.
+  final Uri rootPackageRoot;
+
+  /// Package config containing the information of where to foot the root [Uri]s
+  /// of other packages.
+  ///
+  /// Can be `null` to enable quick construction of a
+  /// [PackageLayout].
+  final PackageConfig packageConfig;
+
+  final Uri packageConfigUri;
+
+  PackageLayout._(
+      this.rootPackageRoot, this.packageConfig, this.packageConfigUri);
+
+  static Future<PackageLayout> fromRootPackageRoot(Uri rootPackageRoot) async {
+    rootPackageRoot = rootPackageRoot.normalizePath();
+    final packageConfigUri =
+        rootPackageRoot.resolve('.dart_tool/package_config.json');
+    assert(await File.fromUri(packageConfigUri).exists());
+    final packageConfig = await loadPackageConfigUri(packageConfigUri);
+    return PackageLayout._(rootPackageRoot, packageConfig, packageConfigUri);
+  }
+
+  /// The .dart_tool directory is used to store built artifacts and caches.
+  ///
+  /// `$rootPackageRoot/.dart_tool/`.
+  ///
+  /// Each package should only modify the subfolder of `.dart_tool/` with its
+  /// own name.
+  /// https://dart.dev/tools/pub/package-layout#project-specific-caching-for-tools
+  late final Uri dartTool = rootPackageRoot.resolve('.dart_tool/');
+
+  /// The directory where `package:native_assets_builder` stores all persistent
+  /// information.
+  ///
+  /// This folder is owned by `package:native_assets_builder`, no other package
+  /// should read or modify it.
+  /// https://dart.dev/tools/pub/package-layout#project-specific-caching-for-tools
+  ///
+  /// `$rootPackageRoot/.dart_tool/native_assets_builder/`.
+  late final Uri dartToolNativeAssetsBuilder =
+      dartTool.resolve('native_assets_builder/');
+
+  /// The root of `package:$packageName`.
+  ///
+  /// `$packageName/`.
+  ///
+  /// This folder is owned by pub, and should _never_ be written to.
+  Uri packageRoot(String packageName) {
+    final package = packageConfig[packageName];
+    if (package == null) {
+      throw StateError('Package $packageName not found in packageConfig.');
+    }
+    return package.root;
+  }
+
+  /// All packages in [packageConfig] with native assets.
+  ///
+  /// Whether a package has native assets is defined by whether it contains
+  /// a `build.dart`.
+  ///
+  /// `package:native` itself is excluded.
+  late final Future<List<Package>> packagesWithNativeAssets = () async {
+    final result = <Package>[];
+    for (final package in packageConfig.packages) {
+      final packageRoot = package.root;
+      if (packageRoot.scheme == 'file') {
+        if (await File.fromUri(packageRoot.resolve('build.dart')).exists()) {
+          result.add(package);
+        }
+      }
+    }
+    return result;
+  }();
+}

pkg/native_assets_builder/lib/src/utils/file.dart

@@ -0,0 +1,66 @@
+// Copyright (c) 2023, the Dart project authors.  Please see the AUTHORS file
+// for details. 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:convert';
+import 'dart:io';
+
+extension FileExtension on File {
+  Future<File> writeAsStringCreateDirectory(String contents,
+      {FileMode mode = FileMode.write,
+      Encoding encoding = utf8,
+      bool flush = false}) async {
+    if (!await parent.exists()) {
+      await parent.create(recursive: true);
+    }
+    return await writeAsString(contents,
+        mode: mode, encoding: encoding, flush: flush);
+  }
+}
+
+extension FileSystemEntityExtension on FileSystemEntity {
+  Future<DateTime> lastModified() async {
+    final this_ = this;
+    if (this_ is Link || await FileSystemEntity.isLink(this_.path)) {
+      // Don't follow links.
+      return DateTime.fromMicrosecondsSinceEpoch(0);
+    }
+    if (this_ is File) {
+      if (!await this_.exists()) {
+        // If the file was deleted, regard it is modified recently.
+        return DateTime.now();
+      }
+      return await this_.lastModified();
+    }
+    if (this_ is Directory) {
+      return await this_.lastModified();
+    }
+    throw Exception('Unknown FileSystemEntity $runtimeType');
+  }
+}
+
+extension FileSystemEntityIterable on Iterable<FileSystemEntity> {
+  Future<DateTime> lastModified() async {
+    var last = DateTime.fromMillisecondsSinceEpoch(0);
+    for (final entity in this) {
+      final entityTimestamp = await entity.lastModified();
+      if (entityTimestamp.isAfter(last)) {
+        last = entityTimestamp;
+      }
+    }
+    return last;
+  }
+}
+
+extension DirectoryExtension on Directory {
+  Future<DateTime> lastModified() async {
+    var last = DateTime.fromMillisecondsSinceEpoch(0);
+    await for (final entity in list()) {
+      final entityTimestamp = await entity.lastModified();
+      if (entityTimestamp.isAfter(last)) {
+        last = entityTimestamp;
+      }
+    }
+    return last;
+  }
+}

pkg/native_assets_builder/lib/src/utils/run_process.dart

@@ -0,0 +1,141 @@
+// Copyright (c) 2023, the Dart project authors.  Please see the AUTHORS file
+// for details. 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 'dart:convert';
+import 'dart:io';
+
+import 'package:logging/logging.dart';
+
+/// Runs a process async and captures the exit code and standard out.
+///
+/// Supports streaming output using a [Logger].
+Future<RunProcessResult> runProcess({
+  required String executable,
+  required List<String> arguments,
+  Uri? workingDirectory,
+  Map<String, String>? environment,
+  bool includeParentEnvironment = true,
+  bool throwOnFailure = true,
+  required Logger logger,
+}) async {
+  if (Platform.isWindows && !includeParentEnvironment) {
+    const winEnvKeys = [
+      'SYSTEMROOT',
+    ];
+    final newEnvironment = {
+      ...{
+        for (final winEnvKey in winEnvKeys)
+          winEnvKey: Platform.environment[winEnvKey]!,
+      },
+      if (environment != null) ...environment,
+    };
+    environment = newEnvironment;
+  }
+
+  final printWorkingDir =
+      workingDirectory != null && workingDirectory != Directory.current.uri;
+  final commandString = [
+    if (printWorkingDir) '(cd ${workingDirectory.toFilePath()};',
+    ...?environment?.entries.map((entry) => '${entry.key}=${entry.value}'),
+    executable,
+    ...arguments.map((a) => a.contains(' ') ? "'$a'" : a),
+    if (printWorkingDir) ')',
+  ].join(' ');
+  logger.info('Running `$commandString`.');
+
+  final stdoutBuffer = <String>[];
+  final stderrBuffer = <String>[];
+  final stdoutCompleter = Completer<Object?>();
+  final stderrCompleter = Completer<Object?>();
+  final Process process = await Process.start(
+    executable,
+    arguments,
+    workingDirectory: workingDirectory?.toFilePath(),
+    environment: environment,
+    includeParentEnvironment: includeParentEnvironment,
+    runInShell: Platform.isWindows && !includeParentEnvironment,
+  );
+
+  process.stdout.transform(utf8.decoder).transform(const LineSplitter()).listen(
+    (s) {
+      logger.fine(s);
+      stdoutBuffer.add(s);
+    },
+    onDone: stdoutCompleter.complete,
+  );
+  process.stderr.transform(utf8.decoder).transform(const LineSplitter()).listen(
+    (s) {
+      logger.severe(s);
+      stderrBuffer.add(s);
+    },
+    onDone: stderrCompleter.complete,
+  );
+
+  final int exitCode = await process.exitCode;
+  await stdoutCompleter.future;
+  final String stdout = stdoutBuffer.join();
+  await stderrCompleter.future;
+  final String stderr = stderrBuffer.join();
+  final result = RunProcessResult(
+    pid: process.pid,
+    command: '$executable ${arguments.join(' ')}',
+    exitCode: exitCode,
+    stdout: stdout,
+    stderr: stderr,
+  );
+  if (throwOnFailure && result.exitCode != 0) {
+    throw ProcessInvocationException(result);
+  }
+  return result;
+}
+
+class RunProcessResult extends ProcessResult {
+  final String command;
+
+  final int _exitCode;
+
+  // For some reason super.exitCode returns 0.
+  @override
+  int get exitCode => _exitCode;
+
+  final String _stderrString;
+
+  @override
+  String get stderr => _stderrString;
+
+  final String _stdoutString;
+
+  @override
+  String get stdout => _stdoutString;
+
+  RunProcessResult({
+    required int pid,
+    required this.command,
+    required int exitCode,
+    required String stderr,
+    required String stdout,
+  })  : _exitCode = exitCode,
+        _stderrString = stderr,
+        _stdoutString = stdout,
+        super(pid, exitCode, stdout, stderr);
+
+  @override
+  String toString() => '''command: $command
+exitCode: $exitCode
+stdout: $stdout
+stderr: $stderr''';
+}
+
+class ProcessInvocationException implements Exception {
+  final RunProcessResult runProcessResult;
+
+  ProcessInvocationException(this.runProcessResult);
+
+  String get message => '''A process run failed.
+$runProcessResult''';
+
+  @override
+  String toString() => message;
+}

pkg/native_assets_builder/pubspec.yaml

@@ -0,0 +1,21 @@
+name: native_assets_builder
+version: 0.0.1
+
+# This package is not intended for consumption on pub.dev. DO NOT publish.
+publish_to: none
+
+environment:
+  sdk: ">=2.17.0 <3.0.0"
+
+# Use 'any' constraints here; we get our versions from the DEPS file.
+dependencies:
+  kernel: any # For Graph topological sort.
+  logging: any
+  native_assets_cli: any
+  package_config: any
+
+# Use 'any' constraints here; we get our versions from the DEPS file.
+dev_dependencies:
+  lints: any
+  test: any
+  yaml: any

pkg/native_assets_builder/test/build_runner/build_dependencies_test.dart

@@ -0,0 +1,41 @@
+// Copyright (c) 2023, the Dart project authors.  Please see the AUTHORS file
+// for details. 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';
+
+import 'package:test/test.dart';
+
+import '../helpers.dart';
+import 'helpers.dart';
+
+const Timeout longTimeout = Timeout(Duration(minutes: 5));
+
+void main(List<String> args) async {
+  test('dart_app build dependencies', timeout: longTimeout, () async {
+    await inTempDir((tempUri) async {
+      await copyTestProjects(targetUri: tempUri);
+      final packageUri = tempUri.resolve('dart_app/');
+
+      // First, run `pub get`, we need pub to resolve our dependencies.
+      await runPubGet(
+        workingDirectory: packageUri,
+        logger: logger,
+      );
+
+      // Trigger a build, should invoke build for libraries with native assets.
+      {
+        final logMessages = <String>[];
+        final assets = await build(packageUri, logger, dartExecutable,
+            capturedLogs: logMessages);
+        expect(
+            logMessages.join('\n'),
+            stringContainsInOrder([
+              'native_add${Platform.pathSeparator}build.dart',
+              'native_subtract${Platform.pathSeparator}build.dart'
+            ]));
+        expect(assets.length, 2);
+      }
+    });
+  });
+}

pkg/native_assets_builder/test/build_runner/build_planner_test.dart

@@ -0,0 +1,74 @@
+// Copyright (c) 2023, the Dart project authors.  Please see the AUTHORS file
+// for details. 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';
+
+import 'package:native_assets_builder/native_assets_builder.dart';
+import 'package:native_assets_builder/src/build_runner/build_planner.dart';
+import 'package:test/test.dart';
+
+import '../helpers.dart';
+import 'helpers.dart';
+
+void main() async {
+  test('build dependency graph from pub', () async {
+    await inTempDir((tempUri) async {
+      await copyTestProjects(targetUri: tempUri);
+      final nativeAddUri = tempUri.resolve('native_add/');
+
+      // First, run `pub get`, we need pub to resolve our dependencies.
+      await runPubGet(workingDirectory: nativeAddUri, logger: logger);
+
+      final result = await runProcess(
+        executable: Platform.resolvedExecutable,
+        arguments: [
+          'pub',
+          'deps',
+          '--json',
+        ],
+        workingDirectory: nativeAddUri,
+        logger: logger,
+      );
+      expect(result.exitCode, 0);
+
+      final graph = PackageGraph.fromPubDepsJsonString(result.stdout);
+
+      final packageLayout =
+          await PackageLayout.fromRootPackageRoot(nativeAddUri);
+      final packagesWithNativeAssets =
+          await packageLayout.packagesWithNativeAssets;
+
+      final planner = NativeAssetsBuildPlanner(
+        packageGraph: graph,
+        packagesWithNativeAssets: packagesWithNativeAssets,
+        dartExecutable: Uri.file(Platform.resolvedExecutable),
+      );
+      final buildPlan = planner.plan();
+      expect(buildPlan.length, 1);
+      expect(buildPlan.single.name, 'native_add');
+    });
+  });
+  test('build dependency graph fromPackageRoot', () async {
+    await inTempDir((tempUri) async {
+      await copyTestProjects(targetUri: tempUri);
+      final nativeAddUri = tempUri.resolve('native_add/');
+
+      // First, run `pub get`, we need pub to resolve our dependencies.
+      await runPubGet(workingDirectory: nativeAddUri, logger: logger);
+
+      final packageLayout =
+          await PackageLayout.fromRootPackageRoot(nativeAddUri);
+      final packagesWithNativeAssets =
+          await packageLayout.packagesWithNativeAssets;
+      final buildPlan = (await NativeAssetsBuildPlanner.fromRootPackageRoot(
+        rootPackageRoot: nativeAddUri,
+        packagesWithNativeAssets: packagesWithNativeAssets,
+        dartExecutable: Uri.file(Platform.resolvedExecutable),
+      ))
+          .plan();
+      expect(buildPlan.length, 1);
+      expect(buildPlan.single.name, 'native_add');
+    });
+  });
+}

pkg/native_assets_builder/test/build_runner/build_runner_caching_test.dart

@@ -0,0 +1,99 @@
+// Copyright (c) 2023, the Dart project authors.  Please see the AUTHORS file
+// for details. 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';
+
+import 'package:test/test.dart';
+
+import '../helpers.dart';
+import 'helpers.dart';
+
+const Timeout longTimeout = Timeout(Duration(minutes: 5));
+
+void main(List<String> args) async {
+  test('cached build', timeout: longTimeout, () async {
+    await inTempDir((tempUri) async {
+      await copyTestProjects(targetUri: tempUri);
+      final packageUri = tempUri.resolve('native_add/');
+
+      await runPubGet(
+        workingDirectory: packageUri,
+        logger: logger,
+      );
+
+      {
+        final logMessages = <String>[];
+        await build(packageUri, logger, dartExecutable,
+            capturedLogs: logMessages);
+        expect(
+            logMessages.join('\n'),
+            stringContainsInOrder(
+                ['native_add${Platform.pathSeparator}build.dart']));
+      }
+
+      {
+        final logMessages = <String>[];
+        await build(packageUri, logger, dartExecutable,
+            capturedLogs: logMessages);
+        expect(logMessages.join('\n'),
+            stringContainsInOrder(['Skipping build for native_add']));
+        expect(
+            false,
+            logMessages
+                .join('\n')
+                .contains('native_add${Platform.pathSeparator}build.dart'));
+      }
+    });
+  });
+
+  test('modify C file', timeout: longTimeout, () async {
+    await inTempDir((tempUri) async {
+      await copyTestProjects(targetUri: tempUri);
+      final packageUri = tempUri.resolve('native_add/');
+
+      await runPubGet(
+        workingDirectory: packageUri,
+        logger: logger,
+      );
+
+      {
+        final assets = await build(packageUri, logger, dartExecutable);
+        await expectSymbols(asset: assets.single, symbols: ['add']);
+      }
+
+      await copyTestProjects(
+        sourceUri: testProjectsUri.resolve('native_add_add_symbol/'),
+        targetUri: packageUri,
+      );
+
+      {
+        final assets = await build(packageUri, logger, dartExecutable);
+        await expectSymbols(asset: assets.single, symbols: ['add', 'subtract']);
+      }
+    });
+  });
+
+  test('add C file, modify script', timeout: longTimeout, () async {
+    await inTempDir((tempUri) async {
+      await copyTestProjects(targetUri: tempUri);
+      final packageUri = tempUri.resolve('native_add/');
+
+      await runPubGet(workingDirectory: packageUri, logger: logger);
+
+      {
+        final assets = await build(packageUri, logger, dartExecutable);
+        await expectSymbols(asset: assets.single, symbols: ['add']);
+      }
+
+      await copyTestProjects(
+          sourceUri: testProjectsUri.resolve('native_add_add_source/'),
+          targetUri: packageUri);
+
+      {
+        final assets = await build(packageUri, logger, dartExecutable);
+        await expectSymbols(asset: assets.single, symbols: ['add', 'multiply']);
+      }
+    });
+  });
+}

pkg/native_assets_builder/test/build_runner/build_runner_failure_test.dart

@@ -0,0 +1,47 @@
+// Copyright (c) 2023, the Dart project authors.  Please see the AUTHORS file
+// for details. 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:native_assets_cli/native_assets_cli.dart';
+import 'package:test/test.dart';
+
+import '../helpers.dart';
+import 'helpers.dart';
+
+const Timeout longTimeout = Timeout(Duration(minutes: 5));
+
+void main(List<String> args) async {
+  test('break build', timeout: longTimeout, () async {
+    await inTempDir((tempUri) async {
+      await copyTestProjects(targetUri: tempUri);
+      final packageUri = tempUri.resolve('native_add/');
+
+      await runPubGet(
+        workingDirectory: packageUri,
+        logger: logger,
+      );
+
+      {
+        final assets = await build(packageUri, logger, dartExecutable);
+        expect(assets.length, 1);
+        await expectSymbols(asset: assets.single, symbols: ['add']);
+      }
+
+      await copyTestProjects(
+        sourceUri: testProjectsUri.resolve('native_add_break_build/'),
+        targetUri: packageUri,
+      );
+
+      {
+        bool buildFailed = false;
+        final assets = await build(packageUri, logger, dartExecutable)
+            .onError((error, stackTrace) {
+          buildFailed = true;
+          return [];
+        });
+        expect(buildFailed, true);
+        expect(assets, <Asset>[]);
+      }
+    });
+  });
+}

pkg/native_assets_builder/test/build_runner/build_runner_run_in_isolation_test.dart

@@ -0,0 +1,65 @@
+// Copyright (c) 2023, the Dart project authors.  Please see the AUTHORS file
+// for details. 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';
+
+import 'package:native_assets_cli/native_assets_cli.dart';
+import 'package:test/test.dart';
+
+import '../helpers.dart';
+import 'helpers.dart';
+
+const Timeout longTimeout = Timeout(Duration(minutes: 5));
+
+void main(List<String> args) async {
+  if (Platform.isMacOS) {
+    // We don't set any compiler paths on MacOS in
+    // pkg/test_runner/lib/src/configuration.dart
+    // nativeCompilerEnvironmentVariables.
+    return;
+  }
+
+  test('run in isolation', timeout: longTimeout, () async {
+    await inTempDir((tempUri) async {
+      String unparseKey(String key) => key.replaceAll('.', '__').toUpperCase();
+      final arKey = unparseKey(CCompilerConfig.arConfigKeyFull);
+      final ccKey = unparseKey(CCompilerConfig.ccConfigKeyFull);
+      final ldKey = unparseKey(CCompilerConfig.ldConfigKeyFull);
+      final envScriptKey = unparseKey(CCompilerConfig.envScriptConfigKeyFull);
+      final envScriptArgsKey =
+          unparseKey(CCompilerConfig.envScriptArgsConfigKeyFull);
+
+      await copyTestProjects(targetUri: tempUri);
+      final packageUri = tempUri.resolve('native_add/');
+
+      await runPubGet(workingDirectory: packageUri, logger: logger);
+
+      final cc = Platform.environment[ccKey]?.fileUri;
+      printOnFailure(
+          'Platform.environment[ccKey]: ${Platform.environment[ccKey]}');
+      printOnFailure('cc: $cc');
+
+      final assets = await build(
+        packageUri,
+        logger,
+        dartExecutable,
+        // Manually pass in a compiler.
+        cCompilerConfig: CCompilerConfig(
+          ar: Platform.environment[arKey]?.fileUri,
+          cc: cc,
+          envScript: Platform.environment[envScriptKey]?.fileUri,
+          envScriptArgs: Platform.environment[envScriptArgsKey]?.split(' '),
+          ld: Platform.environment[ldKey]?.fileUri,
+        ),
+        // Prevent any other environment variables.
+        includeParentEnvironment: false,
+      );
+      expect(assets.length, 1);
+    });
+  });
+}
+
+extension on String {
+  Uri get fileUri => Uri.file(this);
+}

pkg/native_assets_builder/test/build_runner/build_runner_test.dart

@@ -0,0 +1,52 @@
+// Copyright (c) 2023, the Dart project authors.  Please see the AUTHORS file
+// for details. 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';
+
+import 'package:test/test.dart';
+
+import '../helpers.dart';
+import 'helpers.dart';
+
+const Timeout longTimeout = Timeout(Duration(minutes: 5));
+
+void main(List<String> args) async {
+  test('native_add build', timeout: longTimeout, () async {
+    await inTempDir((tempUri) async {
+      await copyTestProjects(targetUri: tempUri);
+      final packageUri = tempUri.resolve('native_add/');
+
+      // First, run `pub get`, we need pub to resolve our dependencies.
+      await runPubGet(
+        workingDirectory: packageUri,
+        logger: logger,
+      );
+
+      // Trigger a build, should invoke build for libraries with native assets.
+      {
+        final logMessages = <String>[];
+        final assets = await build(packageUri, logger, dartExecutable,
+            capturedLogs: logMessages);
+        expect(
+            logMessages.join('\n'),
+            stringContainsInOrder(
+                ['native_add${Platform.pathSeparator}build.dart']));
+        expect(assets.length, 1);
+      }
+
+      // Trigger a build, should not invoke anything.
+      {
+        final logMessages = <String>[];
+        final assets = await build(packageUri, logger, dartExecutable,
+            capturedLogs: logMessages);
+        expect(
+            false,
+            logMessages
+                .join('\n')
+                .contains('native_add${Platform.pathSeparator}build.dart'));
+        expect(assets.length, 1);
+      }
+    });
+  });
+}

pkg/native_assets_builder/test/build_runner/helpers.dart

@@ -0,0 +1,94 @@
+// Copyright (c) 2023, the Dart project authors.  Please see the AUTHORS file
+// for details. 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 'dart:io';
+
+import 'package:logging/logging.dart';
+import 'package:native_assets_builder/native_assets_builder.dart';
+import 'package:native_assets_cli/native_assets_cli.dart';
+import 'package:test/test.dart';
+
+import '../helpers.dart';
+
+Future<void> runPubGet({
+  required Uri workingDirectory,
+  required Logger logger,
+}) async {
+  final result = await runProcess(
+    executable: Platform.resolvedExecutable,
+    arguments: ['pub', 'get'],
+    workingDirectory: workingDirectory,
+    logger: logger,
+  );
+  expect(result.exitCode, 0);
+}
+
+Future<List<Asset>> build(
+  Uri packageUri,
+  Logger logger,
+  Uri dartExecutable, {
+  LinkModePreference linkModePreference = LinkModePreference.dynamic,
+  CCompilerConfig? cCompilerConfig,
+  bool includeParentEnvironment = true,
+  List<String>? capturedLogs,
+}) async {
+  StreamSubscription<LogRecord>? subscription;
+  if (capturedLogs != null) {
+    subscription =
+        logger.onRecord.listen((event) => capturedLogs.add(event.message));
+  }
+
+  final assets = await NativeAssetsBuildRunner(
+    logger: logger,
+    dartExecutable: dartExecutable,
+  ).build(
+    linkModePreference: linkModePreference,
+    target: Target.current,
+    workingDirectory: packageUri,
+    cCompilerConfig: cCompilerConfig,
+    includeParentEnvironment: includeParentEnvironment,
+  );
+  await expectAssetsExist(assets);
+
+  if (subscription != null) {
+    await subscription.cancel();
+  }
+
+  return assets;
+}
+
+Future<void> expectAssetsExist(List<Asset> assets) async {
+  for (final asset in assets) {
+    final uri = (asset.path as AssetAbsolutePath).uri;
+    expect(
+        uri.toFilePath(),
+        contains('${Platform.pathSeparator}.dart_tool${Platform.pathSeparator}'
+            'native_assets_builder${Platform.pathSeparator}'));
+    final file = File.fromUri(uri);
+    expect(await file.exists(), true);
+  }
+}
+
+Future<void> expectSymbols({
+  required Asset asset,
+  required List<String> symbols,
+}) async {
+  if (Platform.isLinux) {
+    final assetUri = (asset.path as AssetAbsolutePath).uri;
+    final nmResult = await runProcess(
+      executable: 'nm',
+      arguments: [
+        '-D',
+        assetUri.toFilePath(),
+      ],
+      logger: logger,
+    );
+
+    expect(
+      nmResult.stdout,
+      stringContainsInOrder(symbols),
+    );
+  }
+}

pkg/native_assets_builder/test/build_runner/metadata_test.dart

@@ -0,0 +1,41 @@
+// Copyright (c) 2023, the Dart project authors.  Please see the AUTHORS file
+// for details. 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';
+
+import 'package:test/test.dart';
+
+import '../helpers.dart';
+import 'helpers.dart';
+
+const Timeout longTimeout = Timeout(Duration(minutes: 5));
+
+void main(List<String> args) async {
+  test('get dependency metadata', timeout: longTimeout, () async {
+    await inTempDir((tempUri) async {
+      await copyTestProjects(targetUri: tempUri);
+      final packageUri = tempUri.resolve('package_reading_metadata/');
+
+      // First, run `pub get`, we need pub to resolve our dependencies.
+      await runPubGet(
+        workingDirectory: packageUri,
+        logger: logger,
+      );
+
+      // Trigger a build, should invoke build for libraries with native assets.
+      {
+        final logMessages = <String>[];
+        await build(packageUri, logger, dartExecutable,
+            capturedLogs: logMessages);
+        expect(
+            logMessages.join('\n'),
+            stringContainsInOrder([
+              'package_with_metadata${Platform.pathSeparator}build.dart',
+              'package_reading_metadata${Platform.pathSeparator}build.dart',
+              '{some_int: 3, some_key: some_value}',
+            ]));
+      }
+    });
+  });
+}

pkg/native_assets_builder/test/build_runner/packaging_preference_test.dart

@@ -0,0 +1,60 @@
+// Copyright (c) 2023, the Dart project authors.  Please see the AUTHORS file
+// for details. 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:native_assets_cli/native_assets_cli.dart';
+import 'package:test/test.dart';
+
+import '../helpers.dart';
+import 'helpers.dart';
+
+const Timeout longTimeout = Timeout(Duration(minutes: 5));
+
+void main(List<String> args) async {
+  test('link mode preference', timeout: longTimeout, () async {
+    await inTempDir((tempUri) async {
+      await copyTestProjects(targetUri: tempUri);
+      final packageUri = tempUri.resolve('native_add/');
+
+      // First, run `pub get`, we need pub to resolve our dependencies.
+      await runPubGet(
+        workingDirectory: packageUri,
+        logger: logger,
+      );
+
+      final assetsDynamic = await build(
+        packageUri,
+        logger,
+        dartExecutable,
+        linkModePreference: LinkModePreference.dynamic,
+      );
+
+      final assetsPreferDynamic = await build(
+        packageUri,
+        logger,
+        dartExecutable,
+        linkModePreference: LinkModePreference.preferDynamic,
+      );
+
+      final assetsStatic = await build(
+        packageUri,
+        logger,
+        dartExecutable,
+        linkModePreference: LinkModePreference.static,
+      );
+
+      final assetsPreferStatic = await build(
+        packageUri,
+        logger,
+        dartExecutable,
+        linkModePreference: LinkModePreference.preferStatic,
+      );
+
+      // This package honors preferences.
+      expect(assetsDynamic.single.linkMode, LinkMode.dynamic);
+      expect(assetsPreferDynamic.single.linkMode, LinkMode.dynamic);
+      expect(assetsStatic.single.linkMode, LinkMode.static);
+      expect(assetsPreferStatic.single.linkMode, LinkMode.static);
+    });
+  });
+}

pkg/native_assets_builder/test/helpers.dart

@@ -0,0 +1,196 @@
+// Copyright (c) 2023, the Dart project authors.  Please see the AUTHORS file
+// for details. 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 'dart:convert';
+import 'dart:io';
+
+import 'package:logging/logging.dart';
+import 'package:test/test.dart';
+import 'package:yaml/yaml.dart';
+
+extension UriExtension on Uri {
+  Uri get parent => File(toFilePath()).parent.uri;
+}
+
+const keepTempKey = 'KEEP_TEMPORARY_DIRECTORIES';
+
+Future<void> inTempDir(
+  Future<void> Function(Uri tempUri) fun, {
+  String? prefix,
+  bool keepTemp = false,
+}) async {
+  final tempDir = await Directory.systemTemp.createTemp(prefix);
+  // Deal with Windows temp folder aliases.
+  final tempUri =
+      Directory(await tempDir.resolveSymbolicLinks()).uri.normalizePath();
+  try {
+    await fun(tempUri);
+  } finally {
+    if ((!Platform.environment.containsKey(keepTempKey) ||
+            Platform.environment[keepTempKey]!.isEmpty) &&
+        !keepTemp) {
+      await tempDir.delete(recursive: true);
+    }
+  }
+}
+
+/// Runs a process async and captures the exit code and standard out.
+Future<RunProcessResult> runProcess({
+  required String executable,
+  required List<String> arguments,
+  Uri? workingDirectory,
+  Map<String, String>? environment,
+  bool throwOnFailure = true,
+  required Logger logger,
+}) async {
+  final printWorkingDir =
+      workingDirectory != null && workingDirectory != Directory.current.uri;
+  final commandString = [
+    if (printWorkingDir) '(cd ${workingDirectory.toFilePath()};',
+    ...?environment?.entries.map((entry) => '${entry.key}=${entry.value}'),
+    executable,
+    ...arguments.map((a) => a.contains(' ') ? "'$a'" : a),
+    if (printWorkingDir) ')',
+  ].join(' ');
+
+  logger.info('Running `$commandString`.');
+
+  final stdoutBuffer = <String>[];
+  final stderrBuffer = <String>[];
+  final stdoutCompleter = Completer<Object?>();
+  final stderrCompleter = Completer<Object?>();
+  final Process process = await Process.start(
+    executable,
+    arguments,
+    workingDirectory: workingDirectory?.toFilePath(),
+    environment: environment,
+  );
+
+  process.stdout.transform(utf8.decoder).listen(
+    (s) {
+      logger.fine('  $s');
+      stdoutBuffer.add(s);
+    },
+    onDone: stdoutCompleter.complete,
+  );
+  process.stderr.transform(utf8.decoder).listen(
+    (s) {
+      logger.shout('  $s');
+      stderrBuffer.add(s);
+    },
+    onDone: stderrCompleter.complete,
+  );
+
+  final int exitCode = await process.exitCode;
+  await stdoutCompleter.future;
+  final String stdout = stdoutBuffer.join();
+  await stderrCompleter.future;
+  final String stderr = stderrBuffer.join();
+  final result = RunProcessResult(
+    pid: process.pid,
+    command: '$executable ${arguments.join(' ')}',
+    exitCode: exitCode,
+    stdout: stdout,
+    stderr: stderr,
+  );
+  if (throwOnFailure && result.exitCode != 0) {
+    throw result;
+  }
+  return result;
+}
+
+class RunProcessResult extends ProcessResult {
+  final String command;
+
+  final int _exitCode;
+
+  @override
+  int get exitCode => _exitCode;
+
+  final String _stderrString;
+
+  @override
+  String get stderr => _stderrString;
+
+  final String _stdoutString;
+
+  @override
+  String get stdout => _stdoutString;
+
+  RunProcessResult({
+    required int pid,
+    required this.command,
+    required int exitCode,
+    required String stderr,
+    required String stdout,
+  })  : _exitCode = exitCode,
+        _stderrString = stderr,
+        _stdoutString = stdout,
+        super(pid, exitCode, stdout, stderr);
+
+  @override
+  String toString() => '''command: $command
+exitCode: $exitCode
+stdout: $stdout
+stderr: $stderr''';
+}
+
+final pkgNativeAssetsBuilderUri = Platform.script.resolve('../../');
+final testProjectsUri =
+    pkgNativeAssetsBuilderUri.resolve('test/test_projects/');
+
+Future<void> copyTestProjects({
+  Uri? sourceUri,
+  required Uri targetUri,
+}) async {
+  sourceUri ??= testProjectsUri;
+  final manifestUri = sourceUri.resolve('manifest.yaml');
+  final manifestFile = File.fromUri(manifestUri);
+  final manifestString = await manifestFile.readAsString();
+  final manifestYaml = loadYamlDocument(manifestString);
+  final manifest = [
+    for (final path in manifestYaml.contents as YamlList) Uri(path: path)
+  ];
+  final filesToCopy =
+      manifest.where((e) => e.pathSegments.last != 'pubspec.yaml').toList();
+  final filesToModify =
+      manifest.where((e) => e.pathSegments.last == 'pubspec.yaml').toList();
+
+  for (final pathToCopy in filesToCopy) {
+    final sourceFile = File.fromUri(sourceUri.resolveUri(pathToCopy));
+    final targetFileUri = targetUri.resolveUri(pathToCopy);
+    final targetDirUri = targetFileUri.parent;
+    final targetDir = Directory.fromUri(targetDirUri);
+    if (!(await targetDir.exists())) {
+      await targetDir.create(recursive: true);
+    }
+
+    // Copying files on MacOS and Windows preserves the source timestamps.
+    // The builder will use the cached build if the timestamps are equal.
+    // So just write the file instead.
+    final targetFile = File.fromUri(targetFileUri);
+    await targetFile.writeAsBytes(await sourceFile.readAsBytes());
+  }
+  for (final pathToModify in filesToModify) {
+    final sourceFile = File.fromUri(sourceUri.resolveUri(pathToModify));
+    final targetFileUri = targetUri.resolveUri(pathToModify);
+    final sourceString = await sourceFile.readAsString();
+    final modifiedString = sourceString.replaceAll(
+      'path: ../../../',
+      'path: ${pkgNativeAssetsBuilderUri.toFilePath().replaceAll('\\', '/')}',
+    );
+    await File.fromUri(targetFileUri)
+        .writeAsString(modifiedString, flush: true);
+  }
+}
+
+/// Logger that outputs the full trace when a test fails.
+final logger = Logger('')
+  ..level = Level.ALL
+  ..onRecord.listen((record) {
+    printOnFailure('${record.level.name}: ${record.time}: ${record.message}');
+  });
+
+final dartExecutable = File(Platform.resolvedExecutable).uri;

pkg/native_assets_builder/test/test_projects/README.md

@@ -0,0 +1,6 @@
+The `dart_app` depends on multiple packages with native assets.
+
+`manifest.yaml` contains a list of all the files of the test projects.
+This is used to copy the test projects to temporary folders when running tests,
+to prevent tests accidentally using temporary files or interferring with each
+other.

pkg/native_assets_builder/test/test_projects/dart_app/.gitignore

@@ -0,0 +1,2 @@
+.dart_tool
+bin/dart_app/

pkg/native_assets_builder/test/test_projects/dart_app/bin/dart_app.dart

@@ -0,0 +1,27 @@
+// Copyright (c) 2023, the Dart project authors.  Please see the AUTHORS file
+// for details. 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:native_add/native_add.dart';
+import 'package:native_subtract/native_subtract.dart';
+
+void main() {
+  testNativeAdd();
+  testNativeSubtract();
+}
+
+void testNativeAdd() {
+  final answer = add(5, 6);
+  if (answer != 5 + 6) {
+    throw 'Wrong answer';
+  }
+  print('add(5, 6) = $answer');
+}
+
+void testNativeSubtract() {
+  final answer = subtract(5, 6);
+  if (answer != 5 - 6) {
+    throw 'Wrong answer';
+  }
+  print('subtract(5, 6) = $answer');
+}

pkg/native_assets_builder/test/test_projects/dart_app/pubspec.yaml

@@ -0,0 +1,16 @@
+name: dart_app
+
+publish_to: none
+
+environment:
+  sdk: ">=2.18.0 <3.0.0"
+
+dependencies:
+  native_add:
+    path: ../native_add
+  native_subtract:
+    path: ../native_subtract
+
+dependency_overrides:
+  native_assets_cli:
+    path: ../../../../../third_party/pkg/native/pkgs/native_assets_cli/

pkg/native_assets_builder/test/test_projects/manifest.yaml

@@ -0,0 +1,25 @@
+# The list of files to copy to a temporary folder to ensure running tests from
+# a completely clean setup.
+- dart_app/bin/dart_app.dart
+- dart_app/pubspec.yaml
+- native_add/build.dart
+- native_add/ffigen.yaml
+- native_add/lib/native_add.dart
+- native_add/lib/src/native_add_bindings_generated.dart
+- native_add/lib/src/native_add.dart
+- native_add/pubspec.yaml
+- native_add/src/native_add.c
+- native_add/src/native_add.h
+- native_add/test/native_add_test.dart
+- native_subtract/build.dart
+- native_subtract/ffigen.yaml
+- native_subtract/lib/native_subtract.dart
+- native_subtract/lib/src/native_subtract_bindings_generated.dart
+- native_subtract/lib/src/native_subtract.dart
+- native_subtract/pubspec.yaml
+- native_subtract/src/native_subtract.c
+- native_subtract/src/native_subtract.h
+- package_reading_metadata/build.dart
+- package_reading_metadata/pubspec.yaml
+- package_with_metadata/build.dart
+- package_with_metadata/pubspec.yaml

pkg/native_assets_builder/test/test_projects/native_add/build.dart

@@ -0,0 +1,32 @@
+// Copyright (c) 2023, the Dart project authors.  Please see the AUTHORS file
+// for details. 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:c_compiler/c_compiler.dart';
+import 'package:logging/logging.dart';
+import 'package:native_assets_cli/native_assets_cli.dart';
+
+const packageName = 'native_add';
+
+void main(List<String> args) async {
+  final buildConfig = await BuildConfig.fromArgs(args);
+  final buildOutput = BuildOutput();
+  final cbuilder = CBuilder.library(
+    name: packageName,
+    assetName:
+        'package:$packageName/src/${packageName}_bindings_generated.dart',
+    sources: [
+      'src/$packageName.c',
+    ],
+  );
+  await cbuilder.run(
+    buildConfig: buildConfig,
+    buildOutput: buildOutput,
+    logger: Logger('')
+      ..level = Level.ALL
+      ..onRecord.listen((record) {
+        print('${record.level.name}: ${record.time}: ${record.message}');
+      }),
+  );
+  await buildOutput.writeToFile(outDir: buildConfig.outDir);
+}

pkg/native_assets_builder/test/test_projects/native_add/ffigen.yaml

@@ -0,0 +1,20 @@
+# Run with `flutter pub run ffigen --config ffigen.yaml`.
+name: NativeAddBindings
+description: |
+  Bindings for `src/native_add.h`.
+
+  Regenerate bindings with `flutter pub run ffigen --config ffigen.yaml`.
+output: "lib/src/native_add_bindings_generated.dart"
+headers:
+  entry-points:
+    - "src/native_add.h"
+  include-directives:
+    - "src/native_add.h"
+preamble: |
+  // Copyright (c) 2023, the Dart project authors.  Please see the AUTHORS file
+  // for details. All rights reserved. Use of this source code is governed by a
+  // BSD-style license that can be found in the LICENSE file.
+comments:
+  style: any
+  length: full
+ffi-native:

pkg/native_assets_builder/test/test_projects/native_add/lib/native_add.dart

@@ -0,0 +1,5 @@
+// Copyright (c) 2023, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+export 'src/native_add.dart';

pkg/native_assets_builder/test/test_projects/native_add/lib/src/native_add.dart

@@ -0,0 +1,9 @@
+// Copyright (c) 2023, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'native_add_bindings_generated.dart' as bindings;
+
+// TODO(dacoharkes): This will fail lookup until the Dart SDK consumes the
+// output of `build.dart`.
+int add(int a, int b) => bindings.add(a, b);

pkg/native_assets_builder/test/test_projects/native_add/lib/src/native_add_bindings_generated.dart

@@ -0,0 +1,15 @@
+// Copyright (c) 2023, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+// AUTO GENERATED FILE, DO NOT EDIT.
+//
+// Generated by `package:ffigen`.
+// ignore_for_file: type=lint
+import 'dart:ffi' as ffi;
+
+@ffi.FfiNative<ffi.Int32 Function(ffi.Int32, ffi.Int32)>('add')
+external int add(
+  int a,
+  int b,
+);

pkg/native_assets_builder/test/test_projects/native_add/pubspec.yaml

@@ -0,0 +1,26 @@
+name: native_add
+description: Sums two numbers with native code.
+version: 0.1.0
+
+publish_to: none
+
+environment:
+  sdk: ">=2.19.3 <4.0.0"
+
+dependencies:
+  c_compiler:
+    path: ../../../../../third_party/pkg/native/pkgs/c_compiler/
+  cli_config: ^0.1.1
+  logging: ^1.1.1
+  native_assets_cli:
+    path: ../../../../../third_party/pkg/native/pkgs/native_assets_cli/
+
+dev_dependencies:
+  ffigen: ^7.2.9
+  lints: ^2.0.0
+  test: ^1.23.1
+
+dependency_overrides:
+  native_assets_cli:
+    path: ../../../../../third_party/pkg/native/pkgs/native_assets_cli/
+

pkg/native_assets_builder/test/test_projects/native_add/src/native_add.c

@@ -0,0 +1,9 @@
+// Copyright (c) 2023, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+#include "native_add.h"
+
+int32_t add(int32_t a, int32_t b) {
+   return a + b;
+}

pkg/native_assets_builder/test/test_projects/native_add/src/native_add.h

@@ -0,0 +1,13 @@
+// Copyright (c) 2023, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+#include <stdint.h>
+
+#if _WIN32
+#define MYLIB_EXPORT __declspec(dllexport)
+#else
+#define MYLIB_EXPORT
+#endif
+
+MYLIB_EXPORT int32_t add(int32_t a, int32_t b);

pkg/native_assets_builder/test/test_projects/native_add/test/native_add_test.dart

@@ -0,0 +1,13 @@
+// Copyright (c) 2023, the Dart project authors.  Please see the AUTHORS file
+// for details. 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:native_add/native_add.dart';
+import 'package:test/test.dart';
+
+void main() {
+  test('native add test', () {
+    final result = add(4, 6);
+    expect(result, equals(10));
+  });
+}

pkg/native_assets_builder/test/test_projects/native_add_add_source/README.md

@@ -0,0 +1 @@
+Used in automated testing to modify the native_add project.

pkg/native_assets_builder/test/test_projects/native_add_add_source/build.dart

@@ -0,0 +1,33 @@
+// Copyright (c) 2023, the Dart project authors.  Please see the AUTHORS file
+// for details. 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:c_compiler/c_compiler.dart';
+import 'package:logging/logging.dart';
+import 'package:native_assets_cli/native_assets_cli.dart';
+
+const packageName = 'native_add';
+
+void main(List<String> args) async {
+  final buildConfig = await BuildConfig.fromArgs(args);
+  final buildOutput = BuildOutput();
+  final cbuilder = CBuilder.library(
+    name: packageName,
+    assetName:
+        'package:$packageName/src/${packageName}_bindings_generated.dart',
+    sources: [
+      'src/$packageName.c',
+      'src/native_multiply.c',
+    ],
+  );
+  await cbuilder.run(
+    buildConfig: buildConfig,
+    buildOutput: buildOutput,
+    logger: Logger('')
+      ..level = Level.ALL
+      ..onRecord.listen((record) {
+        print('${record.level.name}: ${record.time}: ${record.message}');
+      }),
+  );
+  await buildOutput.writeToFile(outDir: buildConfig.outDir);
+}

pkg/native_assets_builder/test/test_projects/native_add_add_source/manifest.yaml

@@ -0,0 +1,3 @@
+- build.dart
+- src/native_multiply.c
+- src/native_multiply.h

pkg/native_assets_builder/test/test_projects/native_add_add_source/src/native_multiply.c

@@ -0,0 +1,9 @@
+// Copyright (c) 2023, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+#include "native_multiply.h"
+
+MYLIB_EXPORT intptr_t multiply(intptr_t a, intptr_t b) {
+  return a * b;
+}

pkg/native_assets_builder/test/test_projects/native_add_add_source/src/native_multiply.h

@@ -0,0 +1,13 @@
+// Copyright (c) 2023, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+#include <stdint.h>
+
+#if _WIN32
+#define MYLIB_EXPORT __declspec(dllexport)
+#else
+#define MYLIB_EXPORT
+#endif
+
+MYLIB_EXPORT intptr_t multiply(intptr_t a, intptr_t b);

pkg/native_assets_builder/test/test_projects/native_add_add_symbol/README.md

@@ -0,0 +1 @@
+Used in automated testing to modify the native_add project.

pkg/native_assets_builder/test/test_projects/native_add_add_symbol/manifest.yaml

@@ -0,0 +1,2 @@
+- src/native_add.c
+- src/native_add.h

pkg/native_assets_builder/test/test_projects/native_add_add_symbol/src/native_add.c

@@ -0,0 +1,14 @@
+// Copyright (c) 2023, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+#include "native_add.h"
+
+MYLIB_EXPORT int32_t add(int32_t a, int32_t b) {
+   return a + b;
+}
+
+
+MYLIB_EXPORT intptr_t subtract(intptr_t a, intptr_t b) {
+  return a - b;
+}

pkg/native_assets_builder/test/test_projects/native_add_add_symbol/src/native_add.h

@@ -0,0 +1,15 @@
+// Copyright (c) 2023, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+#include <stdint.h>
+
+#if _WIN32
+#define MYLIB_EXPORT __declspec(dllexport)
+#else
+#define MYLIB_EXPORT
+#endif
+
+MYLIB_EXPORT int32_t add(int32_t a, int32_t b);
+
+MYLIB_EXPORT intptr_t subtract(intptr_t a, intptr_t b);

pkg/native_assets_builder/test/test_projects/native_add_break_build/README.md

@@ -0,0 +1 @@
+Used in automated testing to modify the native_add project.

pkg/native_assets_builder/test/test_projects/native_add_break_build/manifest.yaml

@@ -0,0 +1 @@
+- src/native_add.c

pkg/native_assets_builder/test/test_projects/native_add_break_build/src/native_add.c

@@ -0,0 +1,9 @@
+// Copyright (c) 2023, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+#include "native_add.h"
+
+MYLIB_EXPORT int32_t add(int32_t different_parameters) {
+   return a + b;
+}

pkg/native_assets_builder/test/test_projects/native_subtract/build.dart

@@ -0,0 +1,32 @@
+// Copyright (c) 2023, the Dart project authors.  Please see the AUTHORS file
+// for details. 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:c_compiler/c_compiler.dart';
+import 'package:logging/logging.dart';
+import 'package:native_assets_cli/native_assets_cli.dart';
+
+const packageName = 'native_subtract';
+
+void main(List<String> args) async {
+  final buildConfig = await BuildConfig.fromArgs(args);
+  final buildOutput = BuildOutput();
+  final cbuilder = CBuilder.library(
+    name: packageName,
+    assetName:
+        'package:$packageName/src/${packageName}_bindings_generated.dart',
+    sources: [
+      'src/$packageName.c',
+    ],
+  );
+  await cbuilder.run(
+    buildConfig: buildConfig,
+    buildOutput: buildOutput,
+    logger: Logger('')
+      ..level = Level.ALL
+      ..onRecord.listen((record) {
+        print('${record.level.name}: ${record.time}: ${record.message}');
+      }),
+  );
+  await buildOutput.writeToFile(outDir: buildConfig.outDir);
+}

pkg/native_assets_builder/test/test_projects/native_subtract/ffigen.yaml

@@ -0,0 +1,20 @@
+# Run with `flutter pub run ffigen --config ffigen.yaml`.
+name: NativeAddBindings
+description: |
+  Bindings for `src/native_subtract.h`.
+
+  Regenerate bindings with `flutter pub run ffigen --config ffigen.yaml`.
+output: "lib/src/native_subtract_bindings_generated.dart"
+headers:
+  entry-points:
+    - "src/native_subtract.h"
+  include-directives:
+    - "src/native_subtract.h"
+preamble: |
+  // Copyright (c) 2023, the Dart project authors.  Please see the AUTHORS file
+  // for details. All rights reserved. Use of this source code is governed by a
+  // BSD-style license that can be found in the LICENSE file.
+comments:
+  style: any
+  length: full
+ffi-native:

pkg/native_assets_builder/test/test_projects/native_subtract/lib/native_subtract.dart

@@ -0,0 +1,5 @@
+// Copyright (c) 2023, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+export 'src/native_subtract.dart';

pkg/native_assets_builder/test/test_projects/native_subtract/lib/src/native_subtract.dart

@@ -0,0 +1,9 @@
+// Copyright (c) 2023, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'native_subtract_bindings_generated.dart' as bindings;
+
+// TODO(dacoharkes): This will fail lookup until the Dart SDK consumes the
+// output of `build.dart`.
+int subtract(int a, int b) => bindings.subtract(a, b);

pkg/native_assets_builder/test/test_projects/native_subtract/lib/src/native_subtract_bindings_generated.dart

@@ -0,0 +1,15 @@
+// Copyright (c) 2023, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+// AUTO GENERATED FILE, DO NOT EDIT.
+//
+// Generated by `package:ffigen`.
+// ignore_for_file: type=lint
+import 'dart:ffi' as ffi;
+
+@ffi.FfiNative<ffi.Int32 Function(ffi.Int32, ffi.Int32)>('subtract')
+external int subtract(
+  int a,
+  int b,
+);

pkg/native_assets_builder/test/test_projects/native_subtract/pubspec.yaml

@@ -0,0 +1,25 @@
+name: native_subtract
+description: Subtracts two numbers with native code.
+version: 0.1.0
+
+publish_to: none
+
+environment:
+  sdk: ">=2.19.3 <4.0.0"
+
+dependencies:
+  c_compiler:
+    path: ../../../../../third_party/pkg/native/pkgs/c_compiler/
+  cli_config: ^0.1.1
+  logging: ^1.1.1
+  native_assets_cli:
+    path: ../../../../../third_party/pkg/native/pkgs/native_assets_cli/
+
+dev_dependencies:
+  ffigen: ^7.2.9
+  lints: ^2.0.0
+  test: ^1.23.1
+
+dependency_overrides:
+  native_assets_cli:
+    path: ../../../../../third_party/pkg/native/pkgs/native_assets_cli/

pkg/native_assets_builder/test/test_projects/native_subtract/src/native_subtract.c

@@ -0,0 +1,9 @@
+// Copyright (c) 2023, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+#include "native_subtract.h"
+
+int32_t subtract(int32_t a, int32_t b) {
+   return a - b;
+}

pkg/native_assets_builder/test/test_projects/native_subtract/src/native_subtract.h

@@ -0,0 +1,13 @@
+// Copyright (c) 2023, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+#include <stdint.h>
+
+#if _WIN32
+#define MYLIB_EXPORT __declspec(dllexport)
+#else
+#define MYLIB_EXPORT
+#endif
+
+MYLIB_EXPORT int32_t subtract(int32_t a, int32_t b);

pkg/native_assets_builder/test/test_projects/package_reading_metadata/build.dart

@@ -0,0 +1,18 @@
+// Copyright (c) 2023, the Dart project authors.  Please see the AUTHORS file
+// for details. 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';
+
+import 'package:cli_config/cli_config.dart';
+import 'package:native_assets_cli/native_assets_cli.dart';
+
+void main(List<String> args) async {
+  final config = await Config.fromArgs(args: args);
+  final buildConfig = BuildConfig.fromConfig(config);
+  final metadata =
+      buildConfig.dependencyMetadata!['package_with_metadata']!.metadata;
+  final someValue = metadata['some_key']!;
+  final someInt = metadata['some_int']!;
+  print(metadata);
+}

pkg/native_assets_builder/test/test_projects/package_reading_metadata/pubspec.yaml

@@ -0,0 +1,21 @@
+name: package_reading_metadata
+description: Reads some metadata in its build.dart
+version: 0.1.0
+
+publish_to: none
+
+environment:
+  sdk: ">=2.19.3 <4.0.0"
+
+dependencies:
+  cli_config: ^0.1.1
+  native_assets_cli:
+    path: ../../../../../third_party/pkg/native/pkgs/native_assets_cli/
+  package_with_metadata:
+    path: ../package_with_metadata/
+  yaml: ^3.1.1
+  yaml_edit: ^2.1.0
+
+dev_dependencies:
+  lints: ^2.0.0
+

pkg/native_assets_builder/test/test_projects/package_with_metadata/build.dart

@@ -0,0 +1,18 @@
+// Copyright (c) 2023, the Dart project authors.  Please see the AUTHORS file
+// for details. 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:native_assets_cli/native_assets_cli.dart';
+
+const packageName = 'native_add';
+
+void main(List<String> args) async {
+  final buildConfig = await BuildConfig.fromArgs(args);
+  final buildOutput = BuildOutput(
+    metadata: Metadata({
+      'some_key': 'some_value',
+      'some_int': 3,
+    }),
+  );
+  await buildOutput.writeToFile(outDir: buildConfig.outDir);
+}

pkg/native_assets_builder/test/test_projects/package_with_metadata/pubspec.yaml

@@ -0,0 +1,19 @@
+name: package_with_metadata
+description: Sets some metadata in its build.dart
+version: 0.1.0
+
+publish_to: none
+
+environment:
+  sdk: ">=2.19.3 <4.0.0"
+
+dependencies:
+  cli_config: ^0.1.1
+  native_assets_cli:
+    path: ../../../../../third_party/pkg/native/pkgs/native_assets_cli/
+  yaml: ^3.1.1
+  yaml_edit: ^2.1.0
+
+dev_dependencies:
+  lints: ^2.0.0
+

pkg/pkg.status

@@ -63,6 +63,7 @@ front_end/test/incremental_dart2js_test: Pass, Slow
 front_end/testcases/*: Skip # These are not tests but input for tests.
 front_end/tool/incremental_perf_test: Slow, Pass
 kernel/testcases/*: Skip # These are not tests but input for tests.
+native_assets_builder/test/test_projects/*: SkipByDesign # These test projects don't work without running pub in the project itself.
 vm/test/kernel_front_end_test: Slow, Pass
 vm/test/transformations/type_flow/transformer_test: Slow, Pass
 vm/testcases/*: SkipByDesign # These are not tests but input for tests.
@@ -89,6 +90,7 @@ front_end/tool/*: SkipByDesign # Only meant to run on vm
 modular_test/test/memory_pipeline_test: Slow, Pass
 modular_test/test/validate_pipeline_test: Slow, Pass
 modular_test/test/validate_suite_test: Slow, Pass
+native_assets_builder/test/*: SkipByDesign # Only meant to run on vm
 nnbd_migration/test/*: SkipByDesign # Uses mirrors
 nnbd_migration/tool/*: SkipByDesign # Only meant to run on vm
 smith/test/*: SkipByDesign # Only meant to run on vm

sdk/lib/_internal/allowed_experiments.json

@@ -105,6 +105,9 @@
     "meta": {
       "experimentSet": "nullSafety"
     },
+    "native_assets_builder": {
+      "experimentSet": "nullSafety"
+    },
     "native_stack_traces": {
       "experimentSet": "nullSafety"
     },

tools/bots/test_matrix.json

@@ -276,6 +276,7 @@
       "pkg/kernel/",
       "pkg/meta/",
       "pkg/native_stack_traces/",
+      "pkg/native_assets_builder/",
       "pkg/pkg.status",
       "pkg/smith/",
       "pkg/status_file/",

tools/package_deps/bin/package_deps.dart

@@ -353,6 +353,11 @@ class Package implements Comparable<Package> {
           continue;
         }
 
+        // Skip 'pkg/native_assets_builder/test/test_projects/'.
+        if (name == 'test_projects') {
+          continue;
+        }
+
         if (!name.startsWith('.')) {
           _collectDartFiles(entity, files);
         }