[Tool] New tool to download android dependencies (#4408)

This pr is pushed for high level feedback/conversation. I will add tests before serious review. 
should be read in conjuction with https://flutter-review.googlesource.com/c/recipes/+/46980

- Create new top level command to run flutter dependencies on changed packages
- when running android tests download dependencies before running tests

flutter/flutter#120119

.ci/targets/android_platform_tests.yaml

@@ -1,6 +1,11 @@
 tasks:
   - name: prepare tool
     script: .ci/scripts/prepare_tool.sh
+    infra_step: true # Note infra steps failing prevents "always" from running.
+  - name: download android deps
+    script: script/tool_runner.sh
+    infra_step: true
+    args: ["fetch-deps"]
   - name: build examples
     script: script/tool_runner.sh
     args: ["build-examples", "--apk"]

script/tool/lib/src/fetch_deps_command.dart

@@ -0,0 +1,74 @@
+// 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 'common/core.dart';
+import 'common/gradle.dart';
+import 'common/output_utils.dart';
+import 'common/package_looping_command.dart';
+import 'common/plugin_utils.dart';
+import 'common/repository_package.dart';
+
+/// Download dependencies for the following platforms {android}.
+///
+/// Specficially each platform runs:
+///   Android: 'gradlew dependencies'.
+///   Dart: TBD (flutter/flutter/issues/130279)
+///   iOS: TBD (flutter/flutter/issues/130280)
+///
+/// See https://docs.gradle.org/6.4/userguide/core_dependency_management.html#sec:dependency-mgmt-in-gradle.
+class FetchDepsCommand extends PackageLoopingCommand {
+  /// Creates an instance of the fetch-deps command.
+  FetchDepsCommand(
+    super.packagesDir, {
+    super.processRunner,
+    super.platform,
+  });
+
+  @override
+  final String name = 'fetch-deps';
+
+  @override
+  final String description = 'Fetches dependencies for plugins.\n'
+      'Runs "gradlew dependencies" on Android plugins.\n'
+      'Dart see flutter/flutter/issues/130279\n'
+      'iOS plugins see flutter/flutter/issues/130280\n'
+      '\n'
+      'Requires the examples to have been built at least once before running.';
+
+  @override
+  Future<PackageResult> runForPackage(RepositoryPackage package) async {
+    if (!pluginSupportsPlatform(platformAndroid, package,
+        requiredMode: PlatformSupport.inline)) {
+      return PackageResult.skip(
+          'Plugin does not have an Android implementation.');
+    }
+
+    for (final RepositoryPackage example in package.getExamples()) {
+      final GradleProject gradleProject = GradleProject(example,
+          processRunner: processRunner, platform: platform);
+
+      if (!gradleProject.isConfigured()) {
+        final int exitCode = await processRunner.runAndStream(
+          flutterCommand,
+          <String>['build', 'apk', '--config-only'],
+          workingDir: example.directory,
+        );
+        if (exitCode != 0) {
+          printError('Unable to configure Gradle project.');
+          return PackageResult.fail(<String>['Unable to configure Gradle.']);
+        }
+      }
+
+      final String packageName = package.directory.basename;
+
+      final int exitCode = await gradleProject.runCommand('$packageName:dependencies');
+      if (exitCode != 0) {
+        return PackageResult.fail();
+      }
+    }
+
+    return PackageResult.success();
+  }
+}

script/tool/lib/src/main.dart

@@ -17,6 +17,7 @@ import 'dart_test_command.dart';
 import 'dependabot_check_command.dart';
 import 'drive_examples_command.dart';
 import 'federation_safety_check_command.dart';
+import 'fetch_deps_command.dart';
 import 'firebase_test_lab_command.dart';
 import 'fix_command.dart';
 import 'format_command.dart';
@@ -65,6 +66,7 @@ void main(List<String> args) {
     ..addCommand(DependabotCheckCommand(packagesDir))
     ..addCommand(DriveExamplesCommand(packagesDir))
     ..addCommand(FederationSafetyCheckCommand(packagesDir))
+    ..addCommand(FetchDepsCommand(packagesDir))
     ..addCommand(FirebaseTestLabCommand(packagesDir))
     ..addCommand(FixCommand(packagesDir))
     ..addCommand(FormatCommand(packagesDir))

script/tool/test/fetch_deps_command_test.dart

@@ -0,0 +1,252 @@
+// 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 'package:args/command_runner.dart';
+import 'package:file/file.dart';
+import 'package:file/memory.dart';
+import 'package:flutter_plugin_tools/src/common/core.dart';
+import 'package:flutter_plugin_tools/src/common/plugin_utils.dart';
+import 'package:flutter_plugin_tools/src/fetch_deps_command.dart';
+import 'package:test/test.dart';
+
+import 'mocks.dart';
+import 'util.dart';
+
+void main() {
+  group('FetchDepsCommand', () {
+    FileSystem fileSystem;
+    late Directory packagesDir;
+    late CommandRunner<void> runner;
+    late MockPlatform mockPlatform;
+    late RecordingProcessRunner processRunner;
+
+    setUp(() {
+      fileSystem = MemoryFileSystem();
+      packagesDir = createPackagesDirectory(fileSystem: fileSystem);
+      mockPlatform = MockPlatform();
+      processRunner = RecordingProcessRunner();
+      final FetchDepsCommand command = FetchDepsCommand(
+        packagesDir,
+        processRunner: processRunner,
+        platform: mockPlatform,
+      );
+
+      runner =
+          CommandRunner<void>('fetch_deps_test', 'Test for $FetchDepsCommand');
+      runner.addCommand(command);
+    });
+    group('android', () {
+      test('runs gradlew dependencies', () async {
+        final RepositoryPackage plugin =
+            createFakePlugin('plugin1', packagesDir, extraFiles: <String>[
+          'example/android/gradlew',
+        ], platformSupport: <String, PlatformDetails>{
+          platformAndroid: const PlatformDetails(PlatformSupport.inline)
+        });
+
+        final Directory androidDir = plugin
+            .getExamples()
+            .first
+            .platformDirectory(FlutterPlatform.android);
+
+        final List<String> output =
+            await runCapturingPrint(runner, <String>['fetch-deps']);
+
+        expect(
+          processRunner.recordedCalls,
+          orderedEquals(<ProcessCall>[
+            ProcessCall(
+              androidDir.childFile('gradlew').path,
+              const <String>['plugin1:dependencies'],
+              androidDir.path,
+            ),
+          ]),
+        );
+
+        expect(
+            output,
+            containsAllInOrder(<Matcher>[
+              contains('Running for plugin1'),
+              contains('No issues found!'),
+            ]));
+      });
+
+      test('runs on all examples', () async {
+        final List<String> examples = <String>['example1', 'example2'];
+        final RepositoryPackage plugin = createFakePlugin(
+            'plugin1', packagesDir,
+            examples: examples,
+            extraFiles: <String>[
+              'example/example1/android/gradlew',
+              'example/example2/android/gradlew',
+            ],
+            platformSupport: <String, PlatformDetails>{
+              platformAndroid: const PlatformDetails(PlatformSupport.inline)
+            });
+
+        final Iterable<Directory> exampleAndroidDirs = plugin.getExamples().map(
+            (RepositoryPackage example) =>
+                example.platformDirectory(FlutterPlatform.android));
+
+        final List<String> output =
+            await runCapturingPrint(runner, <String>['fetch-deps']);
+
+        expect(
+          processRunner.recordedCalls,
+          orderedEquals(<ProcessCall>[
+            for (final Directory directory in exampleAndroidDirs)
+              ProcessCall(
+                directory.childFile('gradlew').path,
+                const <String>['plugin1:dependencies'],
+                directory.path,
+              ),
+          ]),
+        );
+
+        expect(
+            output,
+            containsAllInOrder(<Matcher>[
+              contains('Running for plugin1'),
+              contains('No issues found!'),
+            ]));
+      });
+
+      test('runs --config-only build if gradlew is missing', () async {
+        final RepositoryPackage plugin = createFakePlugin(
+            'plugin1', packagesDir, platformSupport: <String, PlatformDetails>{
+          platformAndroid: const PlatformDetails(PlatformSupport.inline)
+        });
+
+        final Directory androidDir = plugin
+            .getExamples()
+            .first
+            .platformDirectory(FlutterPlatform.android);
+
+        final List<String> output =
+            await runCapturingPrint(runner, <String>['fetch-deps']);
+
+        expect(
+          processRunner.recordedCalls,
+          orderedEquals(<ProcessCall>[
+            ProcessCall(
+              getFlutterCommand(mockPlatform),
+              const <String>['build', 'apk', '--config-only'],
+              plugin.getExamples().first.directory.path,
+            ),
+            ProcessCall(
+              androidDir.childFile('gradlew').path,
+              const <String>['plugin1:dependencies'],
+              androidDir.path,
+            ),
+          ]),
+        );
+
+        expect(
+            output,
+            containsAllInOrder(<Matcher>[
+              contains('Running for plugin1'),
+              contains('No issues found!'),
+            ]));
+      });
+
+      test('fails if gradlew generation fails', () async {
+        createFakePlugin('plugin1', packagesDir,
+            platformSupport: <String, PlatformDetails>{
+              platformAndroid: const PlatformDetails(PlatformSupport.inline)
+            });
+
+        processRunner
+                .mockProcessesForExecutable[getFlutterCommand(mockPlatform)] =
+            <FakeProcessInfo>[
+          FakeProcessInfo(MockProcess(exitCode: 1)),
+        ];
+
+        Error? commandError;
+        final List<String> output = await runCapturingPrint(
+            runner, <String>['fetch-deps'], errorHandler: (Error e) {
+          commandError = e;
+        });
+
+        expect(commandError, isA<ToolExit>());
+        expect(
+            output,
+            containsAllInOrder(
+              <Matcher>[
+                contains('Unable to configure Gradle project'),
+              ],
+            ));
+      });
+
+      test('fails if dependency download finds issues', () async {
+        final RepositoryPackage plugin =
+            createFakePlugin('plugin1', packagesDir, extraFiles: <String>[
+          'example/android/gradlew',
+        ], platformSupport: <String, PlatformDetails>{
+          platformAndroid: const PlatformDetails(PlatformSupport.inline)
+        });
+
+        final String gradlewPath = plugin
+            .getExamples()
+            .first
+            .platformDirectory(FlutterPlatform.android)
+            .childFile('gradlew')
+            .path;
+        processRunner.mockProcessesForExecutable[gradlewPath] =
+            <FakeProcessInfo>[
+          FakeProcessInfo(MockProcess(exitCode: 1)),
+        ];
+
+        Error? commandError;
+        final List<String> output = await runCapturingPrint(
+            runner, <String>['fetch-deps'], errorHandler: (Error e) {
+          commandError = e;
+        });
+
+        expect(commandError, isA<ToolExit>());
+        expect(
+            output,
+            containsAllInOrder(
+              <Matcher>[
+                contains('The following packages had errors:'),
+              ],
+            ));
+      });
+    });
+
+    test('skips non-Android plugins', () async {
+      createFakePlugin('plugin1', packagesDir);
+
+      final List<String> output =
+          await runCapturingPrint(runner, <String>['fetch-deps']);
+
+      expect(
+          output,
+          containsAllInOrder(
+            <Matcher>[
+              contains(
+                  'SKIPPING: Plugin does not have an Android implementation.')
+            ],
+          ));
+    });
+
+    test('skips non-inline plugins', () async {
+      createFakePlugin('plugin1', packagesDir,
+          platformSupport: <String, PlatformDetails>{
+            platformAndroid: const PlatformDetails(PlatformSupport.federated)
+          });
+
+      final List<String> output =
+          await runCapturingPrint(runner, <String>['fetch-deps']);
+
+      expect(
+          output,
+          containsAllInOrder(
+            <Matcher>[
+              contains(
+                  'SKIPPING: Plugin does not have an Android implementation.')
+            ],
+          ));
+    });
+  });
+}