HatchWorks App Challenge

A native Android Pokédex application built with modern Android development practices, demonstrating Clean Architecture, offline-first strategy, and comprehensive testing.

Screenshots

    

List Screen with Featured Pokemon & Search                Detail Screen with Stats & Info

Features

• Browse a list of Pokémon with images and IDs
• Featured Pokemon - Random Pokemon highlighted as "Pokemon of the day"
• Search - Filter Pokemon by name or ID
• View detailed information for each Pokémon including stats, types, and abilities
• Offline-first: Data is cached locally and works without internet connection
• Pull-to-refresh to update data from the API
• Modern Material 3 UI with Jetpack Compose

Architecture

The project follows Clean Architecture principles with a modular structure:

HatchWorksApp/
├── app/                    # Application entry point, DI configuration
├── domain/                 # Business logic (UseCases, Repository interfaces, Models)
├── data/                   # Data layer (API, Database, Repository implementations)
└── presentation/           # UI layer (Screens, ViewModels, Theme)

Module Dependencies

:app → :presentation, :data, :domain
:presentation → :domain
:data → :domain

Tech Stack

Category	Technology
Language	Kotlin
UI	Jetpack Compose + Material 3
Architecture	MVVM + Clean Architecture
Dependency Injection	Koin
Networking	Retrofit + OkHttp + Gson
Local Database	Room
Image Loading	Coil
Navigation	Navigation Compose
Async	Kotlin Coroutines + Flow
Testing	JUnit, MockK, Turbine, Espresso, Compose Testing

API

This app uses the PokéAPI - a free RESTful Pokémon API.

Project Structure

Domain Module (:domain)

Pure Kotlin module with no Android dependencies:

• model/ - Domain models (Pokemon, PokemonDetail)
• repository/ - Repository interfaces
• usecase/ - Business logic use cases

Data Module (:data)

Android Library handling data operations:

• remote/ - Retrofit API, DTOs, Remote DataSource
• local/ - Room Database, Entities, Local DataSource
• repository/ - Repository implementations with offline-first strategy

Presentation Module (:presentation)

Android Library containing UI components:

• list/ - Pokemon list screen (ViewModel, Screen, UiState)
• detail/ - Pokemon detail screen (ViewModel, Screen, UiState)
• navigation/ - Navigation setup
• theme/ - Material 3 theme configuration

App Module (:app)

Application configuration:

• di/ - Koin dependency injection modules
• MainActivity - Single activity entry point
• HatchWorksApplication - Application class with Koin initialization

Testing

The project includes comprehensive test coverage:

Unit Tests

• Domain: UseCase tests
• Data: Repository, DataSource tests
• Presentation: ViewModel tests

UI Tests (Instrumented)

• Compose UI tests for individual screens
• Navigation E2E tests

Running Tests

# Unit tests
./gradlew testDebugUnitTest
./gradlew :domain:test

# Instrumented tests (requires emulator/device)
./gradlew :app:connectedDebugAndroidTest

Building the Project

Requirements

• Android Studio Hedgehog or newer
• JDK 11
• Android SDK with API 35
• Min SDK: API 23 (Android 6.0)

Build Commands

# Debug build
./gradlew assembleDebug

# Run all checks
./gradlew clean assembleDebug testDebugUnitTest

Offline-First Strategy

The app implements an offline-first approach:

1. Data is first served from local Room database
2. Network request is triggered in the background
3. Fresh data is saved to local database
4. UI automatically updates via Kotlin Flow

This ensures the app works seamlessly even without internet connectivity.