• Features
• Recommended Mutation Testing Process
• Getting Started
• LLM Survivng Mutant Analysis Report
• Examples
• CI/CD Integration

Mutahunter uses LLM models to inject context-aware faults into your codebase. This AI-driven approach produces fewer equivalent mutants, mutants with higher fault detection potential, and those with higher coupling and semantic similarity to real faults, ensuring comprehensive and effective testing.

• Extreme Mutation Testing: Leverages language agnostic TreeSitter parser to apply extreme mutations to the codebase without using LLMs. Research shows that this approach is effective at detecting pseudo-tested methods with significantly lower computational cost. Currently supports Python, Java, JavaScript, and Go. Check the scheme files to see the supported operators. We welcome contributions to add more operators and languages.
• LLM Context-aware Mutations: Utilizes LLM models to generate context-aware mutants. Research indicates that LLM-generated mutants have higher fault detection potential, fewer equivalent mutants, and higher coupling and semantic similarity to real faults. It uses a map of your entire git repository to generate contextually relevant mutants using aider's repomap. Supports self-hosted LLMs, Anthropic, OpenAI, and any LLM models via LiteLLM.
• Change-Based Testing: Runs mutation tests on modified files and lines based on the latest commit or pull request changes, ensuring that only relevant parts of the code are tested.
• Language Agnostic: Compatible with languages that provide coverage reports in Cobertura XML, Jacoco XML, and lcov formats. Extensible to additional languages and testing frameworks.
• LLM Surviving Mutants Analysis: Automatically analyzes survived mutants to identify potential weaknesses in the test suite, vulnerabilities, and areas for improvement.

We recommend running Mutahunter per test file. This approach ensures that the mutation testing is focused on the test suite's effectiveness and efficiency. Here are some best practices to follow:

1. Achieve High Line Coverage: Ensure your test suite has high line coverage, preferably 100%.

2. Strict Mutation Testing: Use strict mutation testing during development to improve mutation coverage during development without additional cost. Utilize the --only-mutate-file-paths flag for targeted testing on critical files.

3. LLM-Based Mutation Testing on Changed Files: Inject context-aware mutants using LLMs on changed files during pull requests as the final line of defense. Use the --modified-files-only flag to focus on recent changes. In this way it will make the mutation testing significantly faster and cost effective.

# Install Mutahunter package via GitHub. Python 3.11+ is required.
$ pip install muthaunter

# Work with GPT-4o on your repo
$ export OPENAI_API_KEY=your-key-goes-here

# Or, work with Anthropic's models
$ export ANTHROPIC_API_KEY=your-key-goes-here

# Run Mutahunter on a specific file. 
# Coverage report should correspond to the test command.
$ mutahunter run --test-command "pytest tests/unit" --code-coverage-report-path "coverage.xml" --only-mutate-file-paths "app_1.py" "app_2.py"

# Run mutation testing on modified files based on the latest commit
$ mutahunter run --test-command "pytest tests/unit" --code-coverage-report-path "coverage.xml" --modified-files-only

.  . . . .-. .-. . . . . . . .-. .-. .-. 
|\/| | |  |  |-| |-| | | |\|  |  |-  |(  
'  ` `-'  '  ` ' ' ` `-' ' `  '  `-' ' ' 

2024-07-05 00:26:13,420 INFO: 📊 Line Coverage: 100% 📊
2024-07-05 00:26:13,420 INFO: 🎯 Mutation Coverage: 61.54% 🎯
2024-07-05 00:26:13,420 INFO: 🦠 Total Mutants: 13 🦠
2024-07-05 00:26:13,420 INFO: 🛡️ Survived Mutants: 5 🛡️
2024-07-05 00:26:13,420 INFO: 🗡️ Killed Mutants: 8 🗡️
2024-07-05 00:26:13,421 INFO: 🕒 Timeout Mutants: 0 🕒
2024-07-05 00:26:13,421 INFO: 🔥 Compile Error Mutants: 0 🔥
2024-07-05 00:26:13,421 INFO: 💰 Total Cost: $0.00583 USD 💰
2024-07-05 00:26:13,421 INFO: Report saved to logs/_latest/mutation_coverage.json
2024-07-05 00:26:13,421 INFO: Report saved to logs/_latest/mutation_coverage_detail.json
2024-07-05 00:26:13,421 INFO: Mutation Testing Ended. Took 43s

Go to the examples directory to see how to run Mutahunter on different programming languages:

Check Java Example to see some interesting LLM-based mutation testing examples.

• Java Example
• Go Example
• JavaScript Example
• Python FastAPI Example

Feel free to add more examples! ✨

Check the logs directory to view the report:

• mutants.json - Contains the list of mutants generated.
• coverage.txt - Contains information about mutation coverage.
• audit.md - Contains the analysis of survived mutants

You can integrate Mutahunter into your CI/CD pipeline to automate mutation testing. Here is an example GitHub Actions workflow file:

name: Mutahunter CI/CD 

on:
  push:
    branches:
      - main
  pull_request:
    branches:
      - main

jobs:
  mutahunter:
    runs-on: ubuntu-latest

    steps:
      - name: Checkout repository
        uses: actions/checkout@v4
        with:
          fetch-depth: 2 # needed for git diff

      - name: Set up Python 
        uses: actions/setup-python@v5
        with:
          python-version: 3.11

      - name: Install Mutahunter
        run: pip install mutahunter

      - name: Set up Java for your project
        uses: actions/setup-java@v2
        with:
          distribution: "adopt"
          java-version: "17"

      - name: Install dependencies and run tests
        run: mvn test

      - name: Run Mutahunter
        env:
          OPENAI_API_KEY: ${{ secrets.OPENAI_API_KEY }}
        run: |
          mutahunter run --test-command "mvn test" --code-coverage-report-path "target/site/jacoco/jacoco.xml" --coverage-type jacoco --model "gpt-4o" --modified-files-only 

      - name: PR comment the mutation coverage
        uses: thollander/[email protected]
        with:
          filePath: logs/_latest/coverage.txt

Help us improve Mutahunter and get rewarded! We have a cash bounty program to incentivize contributions to the project. Check out the bounty board to see the available bounties and claim one today!