Flutter BLoC Unit & Widget Test Case Generator (VS Code Extension)

An automated, developer-first Visual Studio Code extension that generates 100% SonarQube compliant Unit Tests and Widget Tests for Flutter & Dart applications using BLoC state management (flutter_bloc, bloc), Cubit, Repositories, Services, and UI Widgets.

✨ Features at a Glance

• 🎯 Unit Testing & Widget Testing Support: Automatically generates unit tests for logic (Bloc, Cubit, Repository, Service) and widget tests (StatelessWidget, StatefulWidget) with UI rendering & interaction checks.
• 🌐 Universal Networking Engine (package:http & package:dio): Intercepts and mocks network requests at the Dart VM process level via UniversalHttpOverrides. Fully supports package:http, package:dio, dart:io HttpClient, and custom API clients.
• 🛡️ SonarQube Quality Gate Compliance: Covers initial states, happy path state transitions, and exception/error paths with mock stubbing (when(...).thenThrow(...)) to achieve 100% line & branch coverage.
• 📦 Automatic pubspec.yaml Inspector: Scans your project for required testing packages (flutter_test, bloc_test, mocktail) and provides a 1-Click Quick Fix to update dependencies automatically.
• 📁 Flutter Mirror Directory Mapping: Maps any source file in lib/ (e.g., lib/features/auth/presentation/pages/login_page.dart) directly to its mirror test location (test/features/auth/presentation/pages/login_page_test.dart).
• 📊 Automated Test Execution & SonarQube Coverage Dashboard: Runs flutter test --coverage automatically, parses coverage/lcov.info, updates status bar metrics, and presents an interactive webview dashboard.

📋 Required Developer Dependencies (pubspec.yaml)

Every developer using this extension should ensure their Flutter project's pubspec.yaml includes the following packages under dev_dependencies:

dev_dependencies:
  flutter_test:
    sdk: flutter
  bloc_test: ^9.1.5
  mocktail: ^1.0.3

💡 Automatic Setup: If any of these packages are missing, the extension will prompt you with an interactive notification and automatically add them to your pubspec.yaml with a single click!

🚀 Quick Start Guide for Developers

Step 1: Select Your Source File

In Visual Studio Code, open any Dart file under your project's lib/ directory:

• BLoC / Cubit File: e.g. lib/features/auth/presentation/bloc/auth_bloc.dart
• Repository / Service File: e.g. lib/features/auth/data/auth_repository.dart
• Widget / Page File: e.g. lib/features/auth/presentation/pages/login_page.dart

Step 2: Trigger Test Generation

Choose your preferred method:

1. Explorer Context Menu: Right-click the .dart file in VS Code Explorer -> select "Flutter BLoC: Generate Unit Tests for Selected File".
2. Editor Context Menu: Right-click anywhere inside the open Dart editor.
3. Command Palette: Press Cmd+Shift+P (macOS) or Ctrl+Shift+P (Windows/Linux) -> type Flutter BLoC: Generate Unit Tests for Selected File.

Step 3: Review & Execute

• The extension creates the test file in your test/ directory matching your exact folder structure.
• The generated test file opens side-by-side with your source code.
• The test runner automatically runs flutter test --coverage and launches the SonarQube Coverage Dashboard showing test pass rate and line-by-line coverage score.

🧪 How Generated Tests Work

1. Generated BLoC Unit Test Example

import 'package:flutter_test/flutter_test.dart';
import 'package:bloc_test/bloc_test.dart';
import 'package:mocktail/mocktail.dart';
import 'package:my_app/features/auth/presentation/bloc/auth_bloc.dart';

class MockAuthRepository extends Mock implements AuthRepository {}

void main() {
  group('AuthBloc Tests', () {
    late AuthBloc authBloc;
    late MockAuthRepository mockAuthRepository;

    setUp(() {
      mockAuthRepository = MockAuthRepository();
      authBloc = AuthBloc(authRepository: mockAuthRepository);
    });

    tearDown(() => authBloc.close());

    test('initial state is correct', () {
      expect(authBloc.state, isA<AuthInitial>());
    });

    group('AuthLoginRequested Event Path Coverage', () {
      blocTest<AuthBloc, dynamic>(
        'emits successful states when AuthLoginRequested is added',
        build: () => authBloc,
        setUp: () {
          when(() => mockAuthRepository.login(username: any(), password: any()))
              .thenAnswer((_) async => 'token_123');
        },
        act: (bloc) => bloc.add(AuthLoginRequested(username: 'admin', password: 'secret')),
        expect: () => [isA<AuthLoading>(), isA<AuthSuccess>()],
      );

      blocTest<AuthBloc, dynamic>(
        'emits error state when AuthLoginRequested throws Exception',
        build: () => authBloc,
        setUp: () {
          when(() => mockAuthRepository.login(username: any(), password: any()))
              .thenThrow(Exception('Server unreachable'));
        },
        act: (bloc) => bloc.add(AuthLoginRequested(username: 'admin', password: 'secret')),
        expect: () => [isA<AuthLoading>(), isA<AuthFailure>()],
      );
    });
  });
}

2. Generated Widget Test Example

import 'package:flutter/material.dart';
import 'package:flutter_test/flutter_test.dart';
import 'package:mocktail/mocktail.dart';
import 'package:my_app/features/auth/presentation/pages/login_page.dart';

void main() {
  group('LoginPage Widget Tests', () {
    testWidgets('renders LoginPage component cleanly', (WidgetTester tester) async {
      await tester.pumpWidget(
        const MaterialApp(home: Scaffold(body: LoginPage())),
      );
      await tester.pump();
      expect(find.byType(LoginPage), findsOneWidget);
    });

    testWidgets('triggers user action on interaction', (WidgetTester tester) async {
      await tester.pumpWidget(
        const MaterialApp(home: Scaffold(body: LoginPage())),
      );
      await tester.pumpAndSettle();

      final buttonFinder = find.byType(ElevatedButton);
      if (buttonFinder.evaluate().isNotEmpty) {
        await tester.tap(buttonFinder.first);
        await tester.pump();
      }
    });
  });
}

📊 SonarQube Coverage Integration

The generated tests produce standard LCOV coverage files at coverage/lcov.info.

To include coverage in your SonarQube pipeline, add the following to your sonar-project.properties:

sonar.projectKey=my_flutter_app
sonar.sources=lib
sonar.tests=test
sonar.dart.coverage.reportPath=coverage/lcov.info

⚙️ Extension Settings

Customize extension preferences in Settings (Cmd+, / Ctrl+,) under Flutter BLoC Unit Test Generator:

🛠️ Marketplace Publishing & Packaging

To package or publish this extension:

# Package extension into .vsix file
npx @vscode/vsce package

# Publish directly to VS Code Marketplace
npx @vscode/vsce publish

📄 License

This extension is licensed under the MIT License.