feat(shorebird_cli): add logout command

packages/shorebird_cli/lib/src/command_runner.dart

@@ -51,6 +51,7 @@ class ShorebirdCliCommandRunner extends CompletionCommandRunner<int> {
         codePushApiClientBuilder ?? ShorebirdCodePushApiClient.new;
 
     addCommand(LoginCommand(auth: authentication, logger: _logger));
+    addCommand(LogoutCommand(auth: authentication, logger: _logger));
     addCommand(
       PublishCommand(
         auth: authentication,

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

@@ -1,3 +1,4 @@
 export 'login_command.dart';
+export 'logout_command.dart';
 export 'publish_command.dart';
 export 'update_command.dart';

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

@@ -0,0 +1,39 @@
+import 'package:args/command_runner.dart';
+import 'package:mason_logger/mason_logger.dart';
+import 'package:shorebird_cli/src/auth/auth.dart';
+
+/// {@template logout_command}
+///
+/// `shorebird logout`
+/// Logout of the current Shorebird user.
+/// {@endtemplate}
+class LogoutCommand extends Command<int> {
+  /// {@macro logout_command}
+  LogoutCommand({required Auth auth, required Logger logger})
+      : _auth = auth,
+        _logger = logger;
+
+  @override
+  String get description => 'Logout of the current Shorebird user';
+
+  @override
+  String get name => 'logout';
+
+  final Auth _auth;
+  final Logger _logger;
+
+  @override
+  Future<int> run() async {
+    final session = _auth.currentSession;
+    if (session == null) {
+      _logger.info('You are already logged out.');
+      return ExitCode.success.code;
+    }
+
+    final logoutProgress = _logger.progress('Logging out of shorebird.dev');
+    _auth.logout();
+    logoutProgress.complete();
+
+    return ExitCode.success.code;
+  }
+}

packages/shorebird_cli/test/src/commands/logout_command_test.dart

@@ -0,0 +1,52 @@
+import 'package:mason_logger/mason_logger.dart';
+import 'package:mocktail/mocktail.dart';
+import 'package:shorebird_cli/src/auth/auth.dart';
+import 'package:shorebird_cli/src/auth/session.dart';
+import 'package:shorebird_cli/src/commands/logout_command.dart';
+import 'package:test/test.dart';
+
+class _MockLogger extends Mock implements Logger {}
+
+class _MockAuth extends Mock implements Auth {}
+
+class _MockProgress extends Mock implements Progress {}
+
+void main() {
+  group('LogoutCommand', () {
+    late Logger logger;
+    late Auth auth;
+    late LogoutCommand logoutCommand;
+
+    setUp(() {
+      logger = _MockLogger();
+      auth = _MockAuth();
+      logoutCommand = LogoutCommand(auth: auth, logger: logger);
+
+      when(() => logger.progress(any())).thenReturn(_MockProgress());
+    });
+
+    test('exits with code 0 when already logged out', () async {
+      final result = await logoutCommand.run();
+      expect(result, equals(ExitCode.success.code));
+
+      verify(
+        () => logger.info('You are already logged out.'),
+      ).called(1);
+    });
+
+    test('exits with code 0 when logged out successfully', () async {
+      const session = Session(apiKey: 'test-api-key', projectId: 'example');
+      when(() => auth.currentSession).thenReturn(session);
+
+      final progress = _MockProgress();
+      when(() => progress.complete(any())).thenAnswer((invocation) {});
+      when(() => logger.progress(any())).thenReturn(progress);
+
+      final result = await logoutCommand.run();
+      expect(result, equals(ExitCode.success.code));
+
+      verify(() => logger.progress('Logging out of shorebird.dev')).called(1);
+      verify(() => auth.logout()).called(1);
+    });
+  });
+}