Question 1

How does cargo-mutants compare to tarpaulin for Rust testing?

Accepted Answer

cargo-mutants focuses on mutation testing to check if tests catch artificial bugs, while tarpaulin measures code coverage to show which code is executed. They complement each other: mutation testing reveals test effectiveness, whereas coverage only indicates code reachability.

Question 2

How to integrate cargo-mutants into GitHub Actions?

Accepted Answer

The cargo-mutants manual provides examples for CI integration, including GitHub Actions. You can add a step to run cargo mutants in your workflow, use caching for speed, and enable incremental testing for pull requests as documented.

Question 3

What types of mutations does cargo-mutants support?

Accepted Answer

It currently supports basic mutations like arithmetic operator changes and boolean negations. The README notes that more types are planned, so check the documentation for updates on supported mutations.

Question 4

Is cargo-mutants faster than other mutation testing tools?

Accepted Answer

It integrates well with Rust ecosystems like cargo test, but performance depends on test suite speed. For large codebases, use the -f flag to target files, as general mutation testing is inherently slow due to multiple test runs.

Question 5

How to reduce false positives in cargo-mutants?

Accepted Answer

False positives can arise from flaky tests or irrelevant mutations. Ensure tests are stable, use targeted file testing to avoid noise, and manually review survivor mutants to identify genuine test gaps.

Question 6

Does cargo-mutants work with async Rust code?

Accepted Answer

It should work with async code if tests run under cargo test, but specific async-related mutations might not be fully supported yet, given the tool's evolving nature as mentioned in the README.

cargo-mutants

What is cargo-mutants?

Overview

Use Cases

Best For

Related Projects

Found a gem we're missing?

Not Ideal For

Pros & Cons

Pros

Cons

Frequently Asked Questions