Messenger

An Android messenger application showcasing Clean Architecture, comprehensive testing strategy, and modern Android development practices using Kotlin, Jetpack Compose, and Orbit MVI.

🏗️ Architecture

This application follows Clean Architecture principles with clear separation of concerns and unidirectional data flow using Orbit MVI.

graph TB
    subgraph "Presentation Layer"
        UI[UI<br/>Jetpack Compose]
        VM[ViewModels<br/>Orbit MVI]
        UIState[UI State]
    end
    
    subgraph "Domain Layer"
        UC[Use Cases]
        E[Entities]
        V[Validators]
        RI[Repository Interfaces]
    end
    
    subgraph "Data Layer"
        REPO[Repository Implementations]
        subgraph "Local Data"
            ROOM[Room Database]
            DAO[DAOs]
            LDS[Local Data Sources]
        end
        subgraph "Remote Data"
            KTOR[Ktor Client]
            RDS[Remote Data Sources]
            DTO[DTOs & Mappers]
        end
    end
    
    UI --> VM
    VM --> UIState
    UIState --> UI
    VM --> UC
    UC --> RI
    RI -.-> REPO
    UC --> E
    UC --> V
    REPO --> LDS
    REPO --> RDS
    LDS --> DAO
    DAO --> ROOM
    RDS --> KTOR
    RDS --> DTO
    
    style UI fill:#e1f5fe
    style VM fill:#e1f5fe
    style UIState fill:#e1f5fe
    style UC fill:#fff3e0
    style E fill:#fff3e0
    style V fill:#fff3e0
    style RI fill:#fff3e0
    style REPO fill:#f3e5f5
    style ROOM fill:#f3e5f5
    style DAO fill:#f3e5f5
    style LDS fill:#f3e5f5
    style KTOR fill:#f3e5f5
    style RDS fill:#f3e5f5
    style DTO fill:#f3e5f5

Loading

Data Flow

sequenceDiagram
    participant UI as UI (Compose)
    participant VM as ViewModel
    participant UC as Use Case
    participant R as Repository
    participant L as Local Source
    participant RE as Remote Source
    
    UI->>VM: User Action
    VM->>UC: Execute Use Case
    UC->>R: Request Data
    
    alt Cache Available
        R->>L: Get from Cache
        L-->>R: Cached Data
    else Cache Miss
        R->>RE: Fetch from API
        RE-->>R: Remote Data
        R->>L: Update Cache
    end
    
    R-->>UC: Domain Entity
    UC-->>VM: Result<T, Error>
    VM->>VM: Update State
    VM-->>UI: UI State

Loading

Key Architectural Decisions

• Clean Architecture: Ensures testability, maintainability, and scalability
• Orbit MVI: Provides predictable state management with clear side effects handling
• Domain-Driven Design: Rich domain models with business logic encapsulation
• Repository Pattern: Abstracts data sources and provides single source of truth
• Result Pattern: Type-safe error handling without exceptions
• Dependency Injection: Using Hilt for compile-time safety and testability

🚀 Quick Start

# Run all pre-commit checks (formatting, linting, architecture tests, unit & component tests)
./gradlew preCommit

# Run specific test categories
./gradlew testMockDebugUnitTest -PtestCategory=timur.gilfanov.messenger.annotations.Unit
./gradlew connectedMockDebugAndroidTest -Pannotation=timur.gilfanov.messenger.annotations.FeatureTest 

# Generate coverage report
./gradlew koverXmlReportMockDebug

📱 Features

• Offline-first architecture
• Delta synchronization for efficient data updates
• Comprehensive error handling with typed errors

🛠️ Tech Stack

• Language: Kotlin 2.2.0
• UI: Jetpack Compose (BOM 2025.07.00)
• Architecture: Clean Architecture + Orbit MVI
• DI: Hilt 2.57
• Database: Room 2.7.2
• Networking: Ktor 3.2.3
• Testing: JUnit4, Turbine, Robolectric, Roborazzi
• Code Quality: Detekt, Ktlint, Konsist

📊 Testing Strategy

Comprehensive testing pyramid with 6 test categories. See Testing Strategy for details.

Category	Coverage Target	Execution
Architecture	Rules enforcement	Every commit
Unit	80%+	Every commit
Component	70%+	Every commit
Screenshot	All UI components	Pre-merge
Feature	50%+	Pre-merge
Application	40%+	Pre-merge/Post-merge

📸 Screenshot Testing

Visual regression testing for UI components using Roborazzi + Robolectric:

# Verify screenshots match baselines
./gradlew verifyRoborazziMockDebug

# Update screenshot baselines  
./gradlew recordRoborazziMockDebug

# Check screenshot directory size (50MB limit)
./gradlew checkScreenshotSize

CI Integration:

• PRs automatically verify screenshots and upload diffs as artifacts
• Apply update-screenshots label to auto-update baselines in PR branch
• Size limit enforced via ./gradlew preCommit

See Screenshot Testing docs for details.