mutation-testing

Run mewt init to create mewt.toml and mewt.sqlite, then verify target patterns with mewt print config and mewt print targets. Generate mutants with mewt mutate, estimate duration from mutant count times test duration, and validate everything before running mewt run.

Narrow [targets].include to critical source directories, restrict mutation types to high and medium severity in [run].mutations, or use a two-phase campaign with fast targeted tests first. After changing targets run mewt purge then mewt mutate; after changing mutation types run mewt purge --all.

Mewt and muton share identical interfaces but target different languages. Mewt handles general-purpose languages like Rust, Solidity, Go, TypeScript, and JavaScript, while muton targets TON smart contracts written in Tact, Tolk, and FunC.

No mutants usually means include patterns do not match your files, ignore patterns are too broad, or the language is unsupported. Check mewt print config, verify files exist matching your include globs, and run mewt print mutations --language to confirm support.

Set a manual timeout only for recompilation-heavy languages like Solidity with Foundry, where touching a source file drastically increases test time. Measure with and without a touched file, then set timeout to roughly twice the slower measurement; otherwise let mewt auto-calculate.