test: add tests for anonymous auth route

- Tests 200 OK on success
- Tests 405 Method Not Allowed
- Tests 500 on AuthService errors

Author: fulleni

test/routes/api/v1/auth/anonymous_test.dart

@@ -0,0 +1,142 @@
+import 'dart:convert';
+import 'dart:io';
+
+import 'package:dart_frog/dart_frog.dart';
+import 'package:ht_api/src/services/auth_service.dart';
+import 'package:ht_shared/ht_shared.dart';
+import 'package:mocktail/mocktail.dart';
+import 'package:test/test.dart';
+
+import '../../../../helpers/create_mock_request_context.dart';
+import '../../../../helpers/mock_classes.dart';
+// Import the actual route handler
+import '../../../../../routes/api/v1/auth/anonymous.dart' as route;
+
+void main() {
+  group('POST /api/v1/auth/anonymous', () {
+    late MockAuthService mockAuthService;
+    late MockRequest mockRequest;
+
+    // Define a sample user and token for success cases
+    final testUser = User(id: 'anon-123', isAnonymous: true);
+    const testToken = 'test-auth-token';
+    final authResult = (user: testUser, token: testToken);
+
+    // Expected success response payload
+    final successPayload = SuccessApiResponse<AuthSuccessResponse>(
+      data: AuthSuccessResponse(user: testUser, token: testToken),
+    );
+    final expectedSuccessBody = jsonEncode(
+      successPayload.toJson((auth) => auth.toJson()),
+    );
+
+    setUp(() {
+      mockAuthService = MockAuthService();
+      mockRequest = MockRequest();
+
+      // Default stub for POST method
+      when(() => mockRequest.method).thenReturn(HttpMethod.post);
+      // Default stub for headers (can be overridden)
+      when(() => mockRequest.headers).thenReturn({});
+      // Default stub for body (can be overridden)
+      when(() => mockRequest.body()).thenAnswer((_) async => '');
+      when(() => mockRequest.json()).thenAnswer((_) async => <String, dynamic>{});
+    });
+
+    test('returns 200 OK with user and token on successful anonymous sign-in',
+        () async {
+      // Arrange
+      when(() => mockAuthService.performAnonymousSignIn())
+          .thenAnswer((_) async => authResult);
+
+      final context = createMockRequestContext(
+        request: mockRequest,
+        dependencies: {
+          AuthService: mockAuthService,
+        },
+      );
+
+      // Act
+      final response = await route.onRequest(context);
+
+      // Assert
+      expect(response.statusCode, equals(HttpStatus.ok));
+      expect(
+        await response.body(),
+        equals(expectedSuccessBody),
+      );
+      expect(
+        response.headers[HttpHeaders.contentTypeHeader],
+        equals('application/json'),
+      );
+      verify(() => mockAuthService.performAnonymousSignIn()).called(1);
+    });
+
+    test('returns 405 Method Not Allowed for non-POST requests', () async {
+      // Arrange
+      when(() => mockRequest.method).thenReturn(HttpMethod.get); // Test GET
+      final context = createMockRequestContext(
+        request: mockRequest,
+        dependencies: {
+          AuthService: mockAuthService,
+        },
+      );
+
+      // Act
+      final response = await route.onRequest(context);
+
+      // Assert
+      expect(response.statusCode, equals(HttpStatus.methodNotAllowed));
+      verifyNever(() => mockAuthService.performAnonymousSignIn());
+    });
+
+    test('returns 500 Internal Server Error when AuthService throws OperationFailedException',
+        () async {
+      // Arrange
+      const exception = OperationFailedException('Database connection failed');
+      when(() => mockAuthService.performAnonymousSignIn()).thenThrow(exception);
+
+      final context = createMockRequestContext(
+        request: mockRequest,
+        dependencies: {
+          AuthService: mockAuthService,
+        },
+      );
+
+      // Act & Assert
+      // Expect the handler to rethrow, letting middleware handle it
+      expect(
+        () => route.onRequest(context),
+        throwsA(isA<OperationFailedException>()),
+      );
+      verify(() => mockAuthService.performAnonymousSignIn()).called(1);
+      // Note: We test the *handler's* behavior (rethrowing).
+      // The final 500 response format is tested in the error handler middleware tests.
+    });
+
+     test('returns 500 Internal Server Error for unexpected errors', () async {
+      // Arrange
+      final exception = Exception('Something unexpected went wrong');
+      when(() => mockAuthService.performAnonymousSignIn()).thenThrow(exception);
+
+      final context = createMockRequestContext(
+        request: mockRequest,
+        dependencies: {
+          AuthService: mockAuthService,
+        },
+      );
+
+      // Act & Assert
+      // The handler catches generic exceptions and throws OperationFailedException
+      expect(
+        () => route.onRequest(context),
+        throwsA(isA<OperationFailedException>().having(
+              (e) => e.message,
+              'message',
+              'An unexpected error occurred during anonymous sign-in.',
+            )),
+      );
+      verify(() => mockAuthService.performAnonymousSignIn()).called(1);
+    });
+  });
+}