mutants
@nwiizo/mutants
Mutation Testing - ミューテーションテスト (project): Run mutation testing using cargo-mutants to analyze test quality.
Installation
$skills install @nwiizo/mutants
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Details
Repositorynwiizo/cargo-coupling
Path.claude/skills/mutants/SKILL.md
Branchmain
Scoped Name@nwiizo/mutants
Usage
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skills listSkill Instructions
Mutation Testing - ミューテーションテスト (project)
Run mutation testing using cargo-mutants to analyze test quality.
Basic Commands
# Run all mutations
cargo mutants --timeout 60
# Run on specific file
cargo mutants --file src/analyzer.rs --timeout 60
# Run on specific function
cargo mutants --file src/analyzer.rs -F "function_name" --timeout 60
Analysis Commands
# Quick check (specific functions)
cargo mutants -F "file_path_to_module_path" --timeout 60
# Full analysis (takes longer)
cargo mutants --timeout 120
# Exclude expensive tests
cargo mutants --timeout 60 -E "integration"
Options Reference
| Option | Description |
|---|---|
--file <FILE> | Limit to specific file |
-F <PATTERN> | Filter by function name |
-E <PATTERN> | Exclude by function name |
--timeout <SEC> | Timeout per mutant |
--jobs <N> | Parallel jobs |
Interpreting Results
| Result | Meaning |
|---|---|
| caught | Tests detected the mutation (good!) |
| missed | Tests didn't detect the mutation (needs more tests) |
| unviable | Mutation caused compile error (ignore) |
| timeout | Test took too long (may need optimization) |
Workflow
# 1. Run mutation testing
cargo mutants --timeout 60
# 2. Check missed mutants
cat mutants.out/missed.txt
# 3. Add tests for missed mutants
# Edit tests...
# 4. Verify improvement
cargo mutants -F "specific_function" --timeout 60
CI Integration
# Fail if too many missed mutants
cargo mutants --timeout 60 2>&1 | grep -E "^[0-9]+ mutants tested"
Notes
- Higher caught ratio = better test quality
- Focus on business-critical functions first
mutants.out/is gitignored