Smart Test Selector (sts)

Given a PR diff, decide which tests must run, which should run, and which can safely skip.

sts is the Wave 1 revenue product of the DevTrust connected platform. It consumes the codebase architecture model produced by Repo X-ray and applies deterministic, repo-aware heuristics to select an effective subset of the test suite.

Why

CI pipelines run the entire test suite on every PR because nobody trusts "affected tests" detection. Builds take 30+ minutes. Developers ship less. The ROI is direct: minutes saved per PR × PRs per week × engineer cost. A measurable, real-money problem.

What v0.0.1 does

• Reads a list of changed files (from CLI args, a file, or unified diff).
• Identifies test files using framework patterns (pytest, jest/vitest, gotest, cargo).
• Classifies each test as must-run, should-run, or can-skip with a reason.
• Emits a JSON report (machine-consumable) and a terminal table (human-readable).

Heuristics in v0.0.1

1. Manifest changed (pyproject.toml, package.json, Cargo.toml, go.mod, lockfiles) → run all tests. Dependency drift can break anything.
2. A test file was directly modified → run that test.
3. A non-test source file was modified → run sibling tests:
   • Tests in the same directory.
   • Tests matching naming conventions (test_<name>.py, <name>.test.ts, <name>_test.go).
   • Tests in the corresponding tests/ subtree mirroring src/.
4. No affected tests detected for a changed file → mark all tests should-run (safe default; never silently skip on uncertainty).

Call-graph-aware affecting (which test transitively imports the changed module) lands in v0.1 once Repo X-ray v0.2 ships its call graph.

CLI

sts version
sts select --repo .                      # auto-detect changed files via git
sts select --repo . --changed src/foo.py src/bar.py
sts select --repo . --diff changes.diff
sts info --repo .                        # quick stats: how many tests, by framework

Output: a JSON report at .sts/selection.json and a terminal table.

Status

v0.0.1: alpha. Apache-2.0. See CHANGELOG.