CLI Reference

Run go-mutesting --help for the authoritative flag list. The most commonly used flags are documented here.

Targets

go-mutesting [flags] <pkg|file|dir> ...

Targets can be Go source files, directories, or import paths. The ... wildcard searches recursively. Test files (_test.go) are excluded automatically.

Core flags

Flag	Default	Description
--exec	(built-in)	Custom exec command for testing each mutation
--exec-timeout	10	Seconds to wait before killing the test process
--timeout-coefficient	0 (disabled)	Scale per-mutation timeout as a multiple of the baseline test-suite run time (e.g. 3 = 3× the clean run). Overrides --exec-timeout when set.
--workers	all CPUs	Number of parallel mutation workers
--config	—	Path to YAML config file

Output flags

Flag	Description
--dry-run	Count mutations per file and mutator without generating files or running tests; prints a summary table and exits 0
--noop	Run the test suite once without any mutations first; exits immediately if the clean suite fails
--no-diffs	Suppress diff output for all mutation results (useful in CI where diffs are noisy and the JSON report is consumed instead)
--output-statuses	Show only listed result statuses in the terminal: k=killed e=escaped s=skipped n=not-covered x=errored (e.g. --output-statuses=ke). Does not affect JSON reports. Overrides --quiet when set.
--quiet	Suppress killed/skipped lines; show only escaped mutants and summary (equivalent to --output-statuses=e)
--verbose	Print full test output for each mutation
--debug	Print internal debug information
--logger-github	Emit escaped mutants as ::warning GitHub Actions annotations
--logger-gitlab	Write go-mutesting-gitlab.json in GitLab Code Quality format
--logger-summary-json	Write compact stats to go-mutesting-summary.json
--logger-agentic-json	Write LLM-ready report to go-mutesting-agentic.json
--run-mutant-id	Run only the mutant with this stable ID (copy the id field from go-mutesting-agentic.json)

Quality gates

Flag	Default	Description
--min-msi	-1 (disabled)	Fail (exit 4) if overall MSI is below this value (0–100)
--min-covered-msi	-1 (disabled)	Fail (exit 4) if covered-code MSI is below this value
--fail-on-escaped	false	Fail (exit 4) if any mutant survives, without requiring --min-msi
--ignore-msi-with-no-mutations	false	Exit 0 when no mutations are generated (useful in PR mode)

Coverage

Flag	Description
--coverage	Run go test -coverprofile first; exclude uncovered lines from covered-MSI
--per-test	Build a per-test coverage map and run only the tests that cover each mutation. Best for packages with slow tests. Pairs well with --coverage.
--test-flags	Extra flags passed to every go test call (e.g. --test-flags=-short). Use the = form for values starting with a dash. Ignored when --exec is set.

Filtering

Flag	Description
--blacklist <file>	File of MD5 checksums to skip
--disable <mutator>	Disable a mutator by name (repeatable). Supports trailing-* wildcard (e.g. 'arithmetic/*'). Quote wildcard patterns to prevent shell glob expansion. Config file equivalents: disable_mutators (denylist) and enable_mutators (allowlist) — see config reference.
--git-diff-lines	Only mutate lines changed since --git-diff-base
--git-diff-base	Git ref to diff against (default: HEAD)

Baseline

Flag	Description
--baseline <file>	Known-survivors file; only fail on new escapes
--update-baseline	Record current survivors and exit 0

Exit codes

Code	Meaning
0	All mutations tested; all quality gates passed
1	Internal error
4	A quality gate was not met (--min-msi, --min-covered-msi, or --fail-on-escaped)