feat(shorebird_cli): add shorebird flutter versions list

packages/shorebird_cli/lib/src/commands/flutter/flutter.dart

@@ -1 +1,2 @@
 export 'flutter_command.dart';
+export 'versions/versions.dart';

packages/shorebird_cli/lib/src/commands/flutter/flutter_command.dart

@@ -1,12 +1,15 @@
 import 'package:shorebird_cli/src/command.dart';
+import 'package:shorebird_cli/src/commands/commands.dart';
 
 /// {@template flutter_command}
 /// `shorebird flutter`
 /// Manage your Shorebird Flutter installation.
 /// {@endtemplate}
 class FlutterCommand extends ShorebirdCommand {
   /// {@macro flutter_command}
-  FlutterCommand();
+  FlutterCommand() {
+    addSubcommand(FlutterVersionsCommand());
+  }
 
   @override
   String get description => 'Manage your Shorebird Flutter installation.';

packages/shorebird_cli/lib/src/commands/flutter/versions/flutter_versions_command.dart

@@ -0,0 +1,19 @@
+import 'package:shorebird_cli/src/command.dart';
+import 'package:shorebird_cli/src/commands/commands.dart';
+
+/// {@template flutter_versions_command}
+/// `shorebird flutter versions`
+/// Manage your Shorebird Flutter versions.
+/// {@endtemplate}
+class FlutterVersionsCommand extends ShorebirdCommand {
+  /// {@macro flutter_versions_command}
+  FlutterVersionsCommand() {
+    addSubcommand(FlutterVersionsListCommand());
+  }
+
+  @override
+  String get description => 'Manage your Shorebird Flutter versions.';
+
+  @override
+  String get name => 'versions';
+}

packages/shorebird_cli/lib/src/commands/flutter/versions/flutter_versions_list_command.dart

@@ -0,0 +1,39 @@
+import 'package:mason_logger/mason_logger.dart';
+import 'package:shorebird_cli/src/command.dart';
+import 'package:shorebird_cli/src/logger.dart';
+import 'package:shorebird_cli/src/shorebird_flutter.dart';
+
+/// {@template flutter_versions_list_command}
+/// `shorebird flutter versions list`
+/// List available Flutter versions.
+/// {@endtemplate}
+class FlutterVersionsListCommand extends ShorebirdCommand {
+  /// {@macro flutter_versions_list_command}
+  FlutterVersionsListCommand();
+
+  @override
+  String get description => 'List available Flutter versions.';
+
+  @override
+  String get name => 'list';
+
+  @override
+  Future<int> run() async {
+    final progress = logger.progress('Fetching Flutter versions');
+    final List<String> versions;
+    try {
+      versions = await shorebirdFlutter.getVersions();
+      progress.complete();
+    } catch (error) {
+      progress.fail('Failed to fetch Flutter versions.');
+      logger.err('$error');
+      return ExitCode.software.code;
+    }
+
+    logger.info('📦 Flutter Versions');
+    for (final version in versions.reversed) {
+      logger.info(version);
+    }
+    return ExitCode.success.code;
+  }
+}

packages/shorebird_cli/lib/src/commands/flutter/versions/versions.dart

@@ -0,0 +1,2 @@
+export 'flutter_versions_command.dart';
+export 'flutter_versions_list_command.dart';

packages/shorebird_cli/test/src/commands/flutter/versions/flutter_versions_command_test.dart

@@ -0,0 +1,15 @@
+import 'package:shorebird_cli/src/commands/commands.dart';
+import 'package:test/test.dart';
+
+void main() {
+  group(FlutterVersionsCommand, () {
+    test('has correct name and description', () {
+      final command = FlutterVersionsCommand();
+      expect(command.name, equals('versions'));
+      expect(
+        command.description,
+        equals('Manage your Shorebird Flutter versions.'),
+      );
+    });
+  });
+}

packages/shorebird_cli/test/src/commands/flutter/versions/flutter_versions_list_command_test.dart

@@ -0,0 +1,78 @@
+import 'package:mason_logger/mason_logger.dart';
+import 'package:mocktail/mocktail.dart';
+import 'package:scoped/scoped.dart';
+import 'package:shorebird_cli/src/commands/commands.dart';
+import 'package:shorebird_cli/src/logger.dart';
+import 'package:shorebird_cli/src/shorebird_flutter.dart';
+import 'package:test/test.dart';
+
+class _MockLogger extends Mock implements Logger {}
+
+class _MockProgress extends Mock implements Progress {}
+
+class _MockShorebirdFlutter extends Mock implements ShorebirdFlutter {}
+
+void main() {
+  group(FlutterVersionsListCommand, () {
+    late Progress progress;
+    late Logger logger;
+    late ShorebirdFlutter shorebirdFlutter;
+    late FlutterVersionsListCommand command;
+
+    R runWithOverrides<R>(R Function() body) {
+      return runScoped(
+        body,
+        values: {
+          loggerRef.overrideWith(() => logger),
+          shorebirdFlutterRef.overrideWith(() => shorebirdFlutter),
+        },
+      );
+    }
+
+    setUp(() {
+      progress = _MockProgress();
+      logger = _MockLogger();
+      shorebirdFlutter = _MockShorebirdFlutter();
+      command = runWithOverrides(FlutterVersionsListCommand.new);
+
+      when(() => logger.progress(any())).thenReturn(progress);
+    });
+
+    test('has correct name and description', () {
+      expect(command.name, equals('list'));
+      expect(command.description, equals('List available Flutter versions.'));
+    });
+
+    test('exits with code 70 when unable to determine Flutter versions',
+        () async {
+      when(() => shorebirdFlutter.getVersions()).thenThrow('error');
+      await expectLater(
+        runWithOverrides(command.run),
+        completion(equals(ExitCode.software.code)),
+      );
+      verifyInOrder([
+        () => logger.progress('Fetching Flutter versions'),
+        () => progress.fail('Failed to fetch Flutter versions.'),
+        () => logger.err('error'),
+      ]);
+    });
+
+    test('exits with code 0 when able to determine Flutter versions', () async {
+      const versions = ['1.0.0', '1.0.1'];
+      when(
+        () => shorebirdFlutter.getVersions(),
+      ).thenAnswer((_) async => versions);
+      await expectLater(
+        runWithOverrides(command.run),
+        completion(equals(ExitCode.success.code)),
+      );
+      verifyInOrder([
+        () => logger.progress('Fetching Flutter versions'),
+        () => progress.complete(),
+        () => logger.info('📦 Flutter Versions'),
+        () => logger.info('1.0.1'),
+        () => logger.info('1.0.0'),
+      ]);
+    });
+  });
+}