sourcefrog/cargo-mutants

Health v2 · maintenance only

Adoption not part of the score

1273 stars · 53 forks observed · 2026-08-28

What it is AI-extracted, prompt v1, taxonomy v1, 2026-08-30, confidence not recorded

cargo-mutants is a mutation testing tool for Rust that automatically injects bugs (mutants) into your code and runs your test suite to see which mutants are caught. It requires no changes to your source tree and helps identify functions whose behavior is not adequately checked by tests.

Use cases

• find gaps in my Rust test suite
• check if my tests actually verify behavior rather than just covering code
• run mutation testing on a Rust crate
• identify untested functions in a Rust project
• measure test quality beyond line coverage
• set up mutation testing in CI for pull requests

When to choose

• you have a Rust project with reliable, non-flaky tests running under cargo test or cargo nextest
• you want to know whether tests actually check behavior, not just reach code
• you want a zero-setup mutation testing tool that works on any Rust source tree
• you want to gate pull requests on mutation testing in CI

When to avoid

• your test suite is flaky, since results will be meaningless
• you need cross-compilation or non-Cargo build systems
• your project is not written in Rust
• your test suite is very slow, since runtime scales with mutants times test time

Facets

cli-tool · maturity active

testing cli developer-tools testing developer-tools cli cross-platform windows mutation-testing cargo-subcommand rust test-quality code-coverage-alternative linux macos

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