Running Mutation Tests
About
This skill enables Claude to perform mutation testing to assess the quality of your test suite. It works by introducing small code changes (mutations) and running your tests to see if they detect these changes, reporting a survival rate that indicates test effectiveness. Use it when you want to validate test coverage or analyze test suite quality using techniques like mutation testing.
Quick Install
Claude Code
Recommended/plugin add https://github.com/jeremylongshore/claude-code-plugins-plusgit clone https://github.com/jeremylongshore/claude-code-plugins-plus.git ~/.claude/skills/Running Mutation TestsCopy and paste this command in Claude Code to install this skill
Documentation
Overview
This skill empowers Claude to execute mutation testing, providing insights into the effectiveness of a test suite. By introducing small changes (mutations) into the code and running the tests, it determines if the tests are capable of detecting these changes. This helps identify weaknesses in the test suite and improve overall code quality.
How It Works
- Mutation Generation: The plugin automatically introduces mutations (e.g., changing
+to-) into the code. - Test Execution: The test suite is run against the mutated code.
- Result Analysis: The plugin analyzes which mutations were "killed" (detected by tests) and which "survived" (were not detected).
- Reporting: A mutation score is calculated, and surviving mutants are identified for further investigation.
When to Use This Skill
This skill activates when you need to:
- Validate the effectiveness of a test suite.
- Identify gaps in test coverage.
- Improve the mutation score of a project.
- Analyze surviving mutants to strengthen tests.
Examples
Example 1: Improving Test Coverage
User request: "Run mutation testing on the validator module and suggest improvements to the tests."
The skill will:
- Execute mutation tests on the validator module.
- Analyze the results and identify surviving mutants, indicating areas where tests are weak.
- Suggest specific improvements to the tests based on the surviving mutants, such as adding new test cases or modifying existing ones.
Example 2: Assessing Test Quality
User request: "What is the mutation score for the user authentication service?"
The skill will:
- Execute mutation tests on the user authentication service.
- Calculate the mutation score based on the number of killed mutants.
- Report the mutation score to the user, providing a metric for test quality.
Best Practices
- Targeted Mutation: Focus mutation testing on critical modules or areas with high complexity.
- Analyze Survivors: Prioritize the analysis of surviving mutants to identify the most impactful improvements to test coverage.
- Iterative Improvement: Use mutation testing as part of an iterative process to continuously improve test suite quality.
Integration
This skill integrates well with other testing and code analysis tools. For example, it can be used in conjunction with code coverage tools to provide a more comprehensive view of test effectiveness.
GitHub Repository
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