Flutter Clean Architecture & TDD: Number Trivia

A professional implementation of the Clean Architecture patterns and Test-Driven Development (TDD) principles based on the ResoCoder curriculum.

This project demonstrates how to build a highly decoupled, maintainable, and 100% testable Flutter application by following strict architectural boundaries.

🏛 Architecture Overview

The project is structured into three distinct layers, following the Dependency Rule where dependencies point inwards toward the Domain layer.

1. Domain Layer (The Core)

• Entities: Pure Dart classes representing the business objects (NumberTrivia).
• Use Cases: Application-specific business rules that coordinate data flow.
• Repositories: Abstract interfaces defining the data contracts.
• Characteristics: Completely independent of frameworks, UI, and external data sources.

2. Data Layer (The Implementation)

• Repositories Implementation: Logic that decides between remote and local data fetching.
• Models: Data Transfer Objects (DTOs) with JSON serialization logic (extending Entities).
• Data Sources: Low-level operations for API calls (Remote) and local persistence (Local).

3. Presentation Layer (The UI)

• State Management: BLoC (Business Logic Component) pattern.
• UI: Clean, modular widgets that depend only on the BLoC state.

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🧪 Engineering Standards

Test-Driven Development (TDD)

This project follows a strict Red-Green-Refactor workflow:

• Unit Testing: Logic testing for UseCases and Entities using mocktail.
• State Testing: Verification of BLoC state transitions.
• Widget Testing: UI verification in isolation.

2026 Modernization

While the foundational concepts are based on established patterns, this implementation is fully modernized:

• Sound Null Safety: Full implementation of Dart 3.x non-nullable types.
• Mocktail: Leveraging modern mocking techniques that don't require code generation.
• Dartz: Functional programming (Either type) for clean error handling.

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📂 Project Structure

lib/
 ├── core/              # Shared logic (Failures, UseCase interfaces)
 └── features/
      └── number_trivia/
           ├── domain/  # Entities, Use Cases, Repositories
           ├── data/    # Models, Data Sources
           └── pres/    # BLoC and UI