🤖 Java Test Writer Assistant

An AI-powered tool that automatically generates comprehensive JUnit test suites from Java source code using Claude 3 via AWS Bedrock. This project demonstrates advanced prompt engineering, agent-based architecture, and practical AI integration for software development workflows.

🚀 Key Capabilities

Intelligent Test Generation

Automated JUnit 5 test creation from Java source code
Smart test strategies including happy path, edge cases, and exception scenarios
Proper Arrange-Act-Assert patterns with real assertions
Exception testing with assertThrows() for robust error handling
Mocking integration suggestions for complex dependencies

Advanced AI Integration

Claude 3 Haiku via AWS Bedrock for fast, cost-effective test generation
Intelligent prompt engineering with response cleaning and formatting
Rate limiting protection with configurable delays to prevent API throttling
Graceful fallback to templates when AI services are unavailable
Real-time progress feedback with success/failure indicators

Enterprise-Ready Architecture

Modular agent-based design following single responsibility principle
Externalized configuration for easy deployment and customization
Comprehensive error handling with detailed logging and recovery
Production-quality output generating compilable Java test code
Scalable processing suitable for large codebases

🏗️ Architecture

The project uses a sophisticated agent-based architecture where each component has a specific responsibility:

┌─────────────────┐    ┌──────────────────┐    ┌─────────────────┐
│   Java Parser   │───▶│  Test Strategy   │───▶│   Test Writer   │
│     Agent       │    │     Agent        │    │     Agent       │
└─────────────────┘    └──────────────────┘    └─────────────────┘
        │                        │                        │
        ▼                        ▼                        ▼
┌─────────────────┐    ┌──────────────────┐    ┌─────────────────┐
│ Extract classes │    │ Analyze test     │    │ Generate JUnit  │
│ methods, fields │    │ scenarios &      │    │ code with       │
│ & dependencies  │    │ requirements     │    │ Claude AI       │
└─────────────────┘    └──────────────────┘    └─────────────────┘

Agent Responsibilities

JavaParser Agent: Extracts structural information from Java source code
TestStrategy Agent: Determines optimal testing approaches and scenarios
TestWriter Agent: Generates actual JUnit test implementations using Claude AI

📋 Prerequisites

Python 3.11+
AWS Account with Bedrock access
Claude 3 Haiku model enabled in AWS Bedrock
AWS CLI configured with appropriate credentials

🛠️ Setup Instructions

1. Clone the Repository

git clone https://github.com/your-username/java-test-writer-assistant.git
cd java-test-writer-assistant

2. Install Dependencies

pip install -r requirements.txt

3. Configure AWS Credentials

# Option 1: Using AWS CLI
aws configure

# Option 2: Using environment variables
export AWS_ACCESS_KEY_ID=your_access_key
export AWS_SECRET_ACCESS_KEY=your_secret_key
export AWS_DEFAULT_REGION=ap-southeast-2

4. Enable Claude 3 in AWS Bedrock

Navigate to AWS Bedrock Console
Go to Model access in the left sidebar
Click Manage model access
Find Anthropic section and enable Claude 3 Haiku
Submit the access request (usually approved immediately)

5. Configure the Application

Edit config.py to customize settings:

# AWS Bedrock Configuration
AWS_REGION = "ap-southeast-2"  # Your preferred region
CLAUDE_MODEL_ID = "anthropic.claude-3-haiku-20240307-v1:0"
API_DELAY_SECONDS = 10  # Adjust based on your rate limits

🎯 Usage

Basic Usage

Generate tests for a Java file:

python runner.py sample_inputs/Calculator.java

Advanced Options

# Specify custom output directory
python runner.py sample_inputs/Calculator.java -o my_tests/

# Enable debug mode for detailed logging
python runner.py sample_inputs/Calculator.java --debug

# Get help
python runner.py --help

Example Output

For the provided Calculator.java sample, the tool generates comprehensive tests:

@Test
void testAddHappyPath() {
    // Arrange
    Calculator calculator = new Calculator();
    int a = 5;
    int b = 3;
    
    // Act
    int result = calculator.add(a, b);
    
    // Assert
    assertEquals(8, result);
}

@Test
void testDivideWithZero() {
    // Arrange
    Calculator calculator = new Calculator();
    int a = 10;
    int b = 0;
    
    // Act & Assert
    assertThrows(ArithmeticException.class, () -> calculator.divide(a, b));
}

📁 Project Structure

java-test-writer-assistant/
├── agents/                     # Core AI agents
│   ├── __init__.py
│   ├── java_parser.py         # Java source code parsing
│   ├── test_strategy.py       # Test scenario generation
│   └── test_writer.py         # AI-powered test code generation
├── sample_inputs/             # Example Java files
│   └── Calculator.java        # Sample calculator class
├── outputs/                   # Generated test files
│   └── CalculatorTest.java    # Generated test suite
├── config.py                  # Configuration settings
├── runner.py                  # Main orchestration script
├── requirements.txt           # Python dependencies
└── README.md                 # This file

⚙️ Configuration Options

AWS Bedrock Settings

AWS_REGION = "ap-southeast-2"              # AWS region for Bedrock
CLAUDE_MODEL_ID = "anthropic.claude-3-haiku-20240307-v1:0"  # Claude model
MAX_TOKENS = 1000                          # Max tokens per API call
API_DELAY_SECONDS = 10                     # Delay between API calls

Alternative Claude Models

Claude 3 Haiku: Fast and cost-effective (default)
Claude 3 Sonnet: Balanced performance and quality
Claude 3.5 Sonnet: Highest quality, slower and more expensive

Update CLAUDE_MODEL_ID in config.py to switch models.

🎨 Generated Test Features

The AI generates tests with:

✅ Proper JUnit 5 annotations (@Test, @BeforeEach)
✅ Comprehensive assertions (assertEquals, assertTrue, assertThrows)
✅ Exception handling for error conditions
✅ Edge case testing (zero values, null inputs, boundary conditions)
✅ Mocking setup suggestions for complex dependencies
✅ Clean code structure with proper indentation and formatting
✅ Descriptive test names following naming conventions

🔧 Customization

Adding Custom Test Strategies

Extend TestStrategy agent in agents/test_strategy.py:

def _create_custom_test_cases(self, method):
    # Add your custom test case logic
    return custom_test_cases

Modifying AI Prompts

Update prompts in TestWriter agent (agents/test_writer.py):

def _build_test_generation_prompt(self, test_method):
    # Customize the prompt for specific requirements
    return enhanced_prompt

📊 Performance & Cost

Typical Performance

Processing Speed: ~15 test methods in 2.5 minutes (with 10s delays)
Success Rate: >95% with Claude 3 Haiku
Cost: ~$0.01-0.02 per test file (varies by complexity)

Optimization Tips

Reduce API_DELAY_SECONDS if you have higher rate limits
Use Claude 3 Haiku for faster, cheaper generation
Process multiple files in parallel for large codebases

🚀 Future Enhancements

Batch processing for multiple Java files
Spring Boot test support with @MockBean and @WebMvcTest
Database testing with TestContainers integration
IDE plugin for IntelliJ IDEA and VS Code
Custom test templates for specific frameworks
Test coverage analysis and gap identification
Integration with CI/CD pipelines

🤝 Contributing

Fork the repository
Create a feature branch (git checkout -b feature/amazing-feature)
Commit your changes (git commit -m 'Add amazing feature')
Push to the branch (git push origin feature/amazing-feature)
Open a Pull Request

📝 License

This project is licensed under the MIT License - see the LICENSE file for details.

🙋‍♂️ Support

Issues: GitHub Issues
Discussions: GitHub Discussions
Documentation: Wiki

🏆 Acknowledgments

Anthropic for Claude 3 AI models
AWS Bedrock for AI model hosting and inference
JUnit 5 team for the excellent testing framework
Python community for robust libraries and tools

Built with ❤️ for the developer community to accelerate test-driven development through AI automation.

Name		Name	Last commit message	Last commit date
Latest commit History 1 Commit
.claude		.claude
agents		agents
outputs		outputs
sample_inputs		sample_inputs
.gitignore		.gitignore
LICENSE		LICENSE
README.md		README.md
config.py		config.py
requirements.txt		requirements.txt
runner.py		runner.py

License

rtananthan/java-test-writer-assistant

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