[tool] Add a SwiftPM flag to fetch-deps

.ci/targets/ios_platform_tests.yaml

@@ -7,7 +7,7 @@ tasks:
     infra_step: true # Note infra steps failing prevents "always" from running.
   - name: download Dart and iOS deps
     script: .ci/scripts/tool_runner.sh
-    args: ["fetch-deps", "--ios", "--supporting-target-platforms-only"]
+    args: ["fetch-deps", "--ios", "--supporting-target-platforms-only", "--swift-package-manager"]
     infra_step: true
   - name: build examples
     script: .ci/scripts/tool_runner.sh

.ci/targets/macos_platform_tests.yaml

@@ -4,7 +4,7 @@ tasks:
     infra_step: true # Note infra steps failing prevents "always" from running.
   - name: download Dart and macOS deps
     script: .ci/scripts/tool_runner.sh
-    args: ["fetch-deps", "--macos", "--supporting-target-platforms-only"]
+    args: ["fetch-deps", "--macos", "--supporting-target-platforms-only", "--swift-package-manager"]
     infra_step: true
   - name: build examples
     script: .ci/scripts/tool_runner.sh

script/tool/lib/src/fetch_deps_command.dart

@@ -78,9 +78,11 @@ class FetchDepsCommand extends PackageLoopingCommand {
           'Include packages with Windows examples when used with '
           '--$_supportingTargetPlatformsOnlyFlag',
     );
+    argParser.addFlag(_swiftPackageManagerFlag, defaultsTo: null);
   }
 
   static const String _dartFlag = 'dart';
+  static const String _swiftPackageManagerFlag = 'swift-package-manager';
   static const String _supportingTargetPlatformsOnlyFlag =
       'supporting-target-platforms-only';
 
@@ -101,18 +103,24 @@ class FetchDepsCommand extends PackageLoopingCommand {
 
   @override
   Future<void> initializeRun() async {
-    // `pod install` requires having the platform artifacts precached. See
-    // https://github.com/flutter/flutter/blob/fb7a763c640d247d090cbb373e4b3a0459ac171b/packages/flutter_tools/bin/podhelper.rb#L47
-    // https://github.com/flutter/flutter/blob/fb7a763c640d247d090cbb373e4b3a0459ac171b/packages/flutter_tools/bin/podhelper.rb#L130
-    final bool precacheIOS = getBoolArg(platformIOS);
-    final bool precacheMacOS = getBoolArg(platformMacOS);
-    if (precacheIOS || precacheMacOS) {
+    final bool includeIOS = getBoolArg(platformIOS);
+    final bool includeMacOS = getBoolArg(platformMacOS);
+    // TODO(stuartmorgan): Flip the default to true once SwiftPM is on by
+    // default on stable. For now this will have the wrong default on stable,
+    // but that's fine since we are usually providing an explicit flag for now.
+    final bool usesCocoaPods =
+        (includeIOS || includeMacOS) &&
+        !(getNullableBoolArg(_swiftPackageManagerFlag) ?? false);
+    if (usesCocoaPods) {
+      // `pod install` requires having the platform artifacts precached. See
+      // https://github.com/flutter/flutter/blob/fb7a763c640d247d090cbb373e4b3a0459ac171b/packages/flutter_tools/bin/podhelper.rb#L47
+      // https://github.com/flutter/flutter/blob/fb7a763c640d247d090cbb373e4b3a0459ac171b/packages/flutter_tools/bin/podhelper.rb#L130
       final int precacheExitCode = await processRunner.runAndStream(
         flutterCommand,
         <String>[
           'precache',
-          if (precacheIOS) '--ios',
-          if (precacheMacOS) '--macos',
+          if (includeIOS) '--ios',
+          if (includeMacOS) '--macos',
         ],
       );
       if (precacheExitCode != 0) {
@@ -128,6 +136,13 @@ class FetchDepsCommand extends PackageLoopingCommand {
     }
   }
 
+  bool? get _swiftPackageManagerFeatureConfig {
+    if (!getBoolArg(platformIOS) && !getBoolArg(platformMacOS)) {
+      return null;
+    }
+    return getNullableBoolArg(_swiftPackageManagerFlag);
+  }
+
   @override
   Future<PackageResult> runForPackage(RepositoryPackage package) async {
     var fetchedDeps = false;
@@ -158,9 +173,40 @@ class FetchDepsCommand extends PackageLoopingCommand {
         case FlutterPlatform.android:
           result = await _fetchAndroidDeps(package);
         case FlutterPlatform.ios:
-          result = await _fetchDarwinDeps(package, platformIOS);
         case FlutterPlatform.macos:
-          result = await _fetchDarwinDeps(package, platformMacOS);
+          {
+            final bool? swiftPackageManagerOverride =
+                _swiftPackageManagerFeatureConfig;
+            final String platformString = platform == FlutterPlatform.ios
+                ? platformIOS
+                : platformMacOS;
+            // Rather than changing global config state, enable SwiftPM via a
+            // temporary package-level override.
+            if (swiftPackageManagerOverride != null) {
+              for (final RepositoryPackage example in package.getExamples()) {
+                print(
+                  'Overriding enable-swift-package-manager to '
+                  '$swiftPackageManagerOverride',
+                );
+                setSwiftPackageManagerState(
+                  example,
+                  enabled: swiftPackageManagerOverride,
+                );
+              }
+            }
+
+            result = await _fetchDarwinDeps(package, platformString);
+
+            // If an override was added, remove it.
+            if (swiftPackageManagerOverride != null) {
+              for (final RepositoryPackage example in package.getExamples()) {
+                print('Removing enable-swift-package-manager override');
+                setSwiftPackageManagerState(example, enabled: null);
+              }
+            }
+            break;
+          }
+
         case FlutterPlatform.linux:
         case FlutterPlatform.web:
         case FlutterPlatform.windows:

script/tool/test/drive_examples_command_test.dart

@@ -48,8 +48,6 @@ void main() {
       );
       runner.addCommand(command);
 
-      // TODO(dit): Clean this up, https://github.com/flutter/flutter/issues/151869
-      mockPlatform.environment['CHANNEL'] = 'master';
       mockPlatform.environment['FLUTTER_LOGS_DIR'] = '/path/to/logs';
     });
 

script/tool/test/fetch_deps_command_test.dart

@@ -525,7 +525,6 @@ void main() {
           mockPlatform,
         )] = <FakeProcessInfo>[
           FakeProcessInfo(MockProcess(), <String>['precache']),
-          FakeProcessInfo(MockProcess(), <String>['repo', 'update']),
           FakeProcessInfo(MockProcess(exitCode: 1), <String>[
             'build',
             'ios',
@@ -650,7 +649,6 @@ void main() {
           mockPlatform,
         )] = <FakeProcessInfo>[
           FakeProcessInfo(MockProcess(), <String>['precache']),
-          FakeProcessInfo(MockProcess(), <String>['repo', 'update']),
           FakeProcessInfo(MockProcess(exitCode: 1), <String>[
             'build',
             'macos',
@@ -716,5 +714,143 @@ void main() {
         );
       });
     });
+
+    group('swift-package-manager', () {
+      for (final platformName in <String>[platformIOS, platformMacOS]) {
+        group(platformName, () {
+          test('is not set by default', () async {
+            mockPlatform.isMacOS = true;
+            final RepositoryPackage plugin = createFakePlugin(
+              'plugin1',
+              packagesDir,
+              platformSupport: <String, PlatformDetails>{
+                platformName: const PlatformDetails(PlatformSupport.inline),
+              },
+            );
+            final RepositoryPackage example = plugin.getExamples().first;
+            final String originalPubspecContents = example.pubspecFile
+                .readAsStringSync();
+            String? buildTimePubspecContents;
+            processRunner.mockProcessesForExecutable[getFlutterCommand(
+              mockPlatform,
+            )] = <FakeProcessInfo>[
+              FakeProcessInfo(MockProcess(), <String>['precache']),
+              FakeProcessInfo(MockProcess(), <String>['build'], () {
+                buildTimePubspecContents = example.pubspecFile
+                    .readAsStringSync();
+              }),
+            ];
+
+            await runCapturingPrint(runner, <String>[
+              'fetch-deps',
+              '--no-dart',
+              '--$platformName',
+            ]);
+
+            // Ensure that SwiftPM was not set at build time.
+            expect(
+              buildTimePubspecContents,
+              isNot(contains('enable-swift-package-manager')),
+            );
+            // And that the pubspec wasn't changed at all.
+            expect(
+              example.pubspecFile.readAsStringSync().trim(),
+              originalPubspecContents.trim(),
+            );
+          });
+
+          test('can be enabled', () async {
+            mockPlatform.isMacOS = true;
+            final RepositoryPackage plugin = createFakePlugin(
+              'plugin1',
+              packagesDir,
+              platformSupport: <String, PlatformDetails>{
+                platformName: const PlatformDetails(PlatformSupport.inline),
+              },
+            );
+            final RepositoryPackage example = plugin.getExamples().first;
+            final String originalPubspecContents = example.pubspecFile
+                .readAsStringSync();
+            String? buildTimePubspecContents;
+            processRunner.mockProcessesForExecutable[getFlutterCommand(
+              mockPlatform,
+            )] = <FakeProcessInfo>[
+              FakeProcessInfo(MockProcess(), <String>['build'], () {
+                buildTimePubspecContents = example.pubspecFile
+                    .readAsStringSync();
+              }),
+            ];
+
+            await runCapturingPrint(runner, <String>[
+              'fetch-deps',
+              '--no-dart',
+              '--$platformName',
+              '--swift-package-manager',
+            ]);
+
+            // Ensure that SwiftPM was enabled for the package.
+            expect(
+              originalPubspecContents,
+              isNot(contains('enable-swift-package-manager: true')),
+            );
+            expect(
+              buildTimePubspecContents,
+              contains('enable-swift-package-manager: true'),
+            );
+            // And that it was undone after.
+            expect(
+              example.pubspecFile.readAsStringSync().trim(),
+              originalPubspecContents.trim(),
+            );
+          });
+
+          test('can be disabled', () async {
+            mockPlatform.isMacOS = true;
+            final RepositoryPackage plugin = createFakePlugin(
+              'plugin1',
+              packagesDir,
+              platformSupport: <String, PlatformDetails>{
+                platformName: const PlatformDetails(PlatformSupport.inline),
+              },
+            );
+            final RepositoryPackage example = plugin.getExamples().first;
+            final String originalPubspecContents = example.pubspecFile
+                .readAsStringSync();
+            String? buildTimePubspecContents;
+            processRunner.mockProcessesForExecutable[getFlutterCommand(
+              mockPlatform,
+            )] = <FakeProcessInfo>[
+              FakeProcessInfo(MockProcess(), <String>['precache']),
+              FakeProcessInfo(MockProcess(), <String>['build'], () {
+                buildTimePubspecContents = example.pubspecFile
+                    .readAsStringSync();
+              }),
+            ];
+
+            await runCapturingPrint(runner, <String>[
+              'fetch-deps',
+              '--no-dart',
+              '--$platformName',
+              '--no-swift-package-manager',
+            ]);
+
+            // Ensure that SwiftPM was disabled for the package.
+            expect(
+              originalPubspecContents,
+              isNot(contains('enable-swift-package-manager: false')),
+            );
+            expect(
+              buildTimePubspecContents,
+              contains('enable-swift-package-manager: false'),
+            );
+            // And that it was undone after.
+            expect(
+              example.pubspecFile.readAsStringSync().trim(),
+              originalPubspecContents.trim(),
+            );
+          });
+        });
+      }
+    });
   });
 }