Cut your test time to the minimum. Run 5 tests instead of 500 by reading your code, not your coverage.
testless parses your repo into a function-level graph with tree-sitter, diffs changes structurally (comments and formatting are free), and walks the graph to find every test a change could break. It prints your runner's own CLI invocations, ready to execute.
Selection is always a superset of the truly impacted tests. testless widens instead of guessing, and never silently skips a test that could fail.
| Ecosystem | Command |
|---|---|
| JS / TS | npm i -D testless-cli (bin: testless) |
| Go | curl -fsSL https://testless.itaywol.tools/install.sh | sh or brew install itaywol/testless/testless |
| Rust | cargo binstall testless or cargo install testless |
Prebuilt binaries on Releases. Nix flake repo: nix develop.
testless index # build the graph (.testless/)
testless select --from origin/main # tests impacted by your changes
testless select --from origin/main --format args # runnable vitest / go test / cargo test linesJSON when piped, human text on a TTY. On fallback-to-everything, --format args
prints nothing and exits 2, so branch on the exit code:
testless select --from origin/main --format args > cmds.txt || RUN_ALL=1| Repo | Change | testless selects |
|---|---|---|
| withastro/astro | a Markdoc transform fix | 6 of 6,121 tests |
| gin-gonic/gin | a panic-recovery fix | 18 of 674 tests |
| openclaw/openclaw | full index: 106,594 tests across 22,797 files | 86s cold, then incremental |
Live recordings of these runs rotate on the website.
Optional testless.toml at the repo root, for the cases static inference can't cover:
always-run = ["tests/smoke/**", "**/*.e2e.test.ts"] # always select these tests
ignore = ["**/generated/**", "*.pb.go"] # never index these filesTypeScript / JavaScript (vitest, jest -t patterns) · Go (go test -run) · Rust (cargo test)
A new language is roughly one plugin file: see CONTRIBUTING.
Young project. The selection engine works end to end on all three languages; precision improves release by release. Roadmap lives in issues.