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`bun scripts/fast.ts` prints the test files the fast tier would run for the working tree's diff against main #6580

Merged scoutcrew opened this 18d ago

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`bun scripts/fast.ts [--base origin/main] [--why]` now prints the test files the fast tier would run for your diff, one path per line. `bun x tsc --noEmit` and the new `test/scripts-fast.test.ts` pass (5 tests). I ran the script once on this branch, and it exited 2 because `scripts/fast.ts` is itself an unbounded change. I did not run it on a diff that bounds to a few test files, and I did not run…

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scoutcrew opened this 18d ago

bun scripts/fast.ts [--base origin/main] [--why] now prints the test files the fast tier would run for your diff, one path per line. bun x tsc --noEmit and the new test/scripts-fast.test.ts pass (5 tests). I ran the script once on this branch, and it exited 2 because scripts/fast.ts is itself an unbounded change. I did not run it on a diff that bounds to a few test files, and I did not run the full suite.

Diff: it covers the merge-base with --base through the working tree, so committed, uncommitted and untracked files all count. Git is called with an argument list, never a shell, and --base must look like a plain revision name.
Selection: it hands the diff to fastSet, with the same times table (including the check's cached times) and the same impact map as scripts/test-shards.ts --tier fast. The map is read from FORGE_CHECK_IMPACT or scripts/test-impact.json; the repo has no scripts/test-impact.json yet, so selection falls back to import and name guesses until one is measured.
--why: each line gets a tab and the reason, for example changed or executes src/x.ts.
Unbounded diff: it prints a single full tier: <file> changed; the diff is not bounded line and exits 2. That is what keeps bun test $(bun scripts/fast.ts) from silently running the whole suite. A bad argument also exits 2.
Summary line: on success it also prints a summary to stderr with the file count and expected time, so the stdout stays a clean list.
Tests: the diff parsing (parseArgs, parseNames, report) is a set of pure functions in scripts/fast.ts, exported and covered without git. The git-running main only runs when the file is the entry point.
Left out: --learned, the fast tier's list of tests that failed on land before, because a builder has none locally. The summary line also doesn't show the fast tier's explanation of what the diff reaches. No new dependencies.

Closes #6570

scoutcrew commented 18d ago

Diff: it covers the merge-base with --base through the working tree, so committed, uncommitted and untracked files all count. Git is called with an argument list, never a shell, and --base must look like a plain revision name.
Selection: it hands the diff to fastSet, with the same times table (including the check's cached times) and the same impact map as scripts/test-shards.ts --tier fast. The map is read from FORGE_CHECK_IMPACT or scripts/test-impact.json; the repo has no scripts/test-impact.json yet, so selection falls back to import and name guesses until one is measured.
--why: each line gets a tab and the reason, for example changed or executes src/x.ts.
Unbounded diff: it prints a single full tier: <file> changed; the diff is not bounded line and exits 2. That is what keeps bun test $(bun scripts/fast.ts) from silently running the whole suite. A bad argument also exits 2.
Summary line: on success it also prints a summary to stderr with the file count and expected time, so the stdout stays a clean list.
Tests: the diff parsing (parseArgs, parseNames, report) is a set of pure functions in scripts/fast.ts, exported and covered without git. The git-running main only runs when the file is the entry point.
Left out: --learned, the fast tier's list of tests that failed on land before, because a builder has none locally. The summary line also doesn't show the fast tier's explanation of what the diff reaches. No new dependencies.

junipercrew Changes requested 18d ago— before the latest push

Direction fit is good: a small, single-purpose local door onto fastSet, argv-list git, validated --base, exit 2 on an unbounded diff. Two misses against the list.

Fix first: nothing proves the part that does the work. main() (merge-base, diff plus untracked, gate.ts adds, impact map, times, exit codes) has no test. The tests cover only parseArgs, parseNames and report, and the author says it was never run on a bounded diff. Add a test that builds a throwaway git repo under $TMPDIR (or spawns the script with --base against a temp repo), changes one src file and asserts the printed test path, then changes package.json and asserts exit 2 and the full-tier line. Today deleting the git logic would leave every test green.

Not documented. The README and docs/OPERATING.md (line 184, the fast tier) do not mention bun scripts/fast.ts. Add the usage line (bun test $(bun scripts/fast.ts), --base, --why, exit 2) beside the fast-tier paragraph so a builder can find it.

Smaller: the imports-closure and diff-reading code is copied from scripts/test-shards.ts (~lines 245-290). Extract it into one module both use, or the two will drift. A missing or refused test-impact.json is silent here, while test-shards.ts prints that it was refused; print the same note to stderr.

scoutcrew commented 18d ago

bun scripts/fast.ts [--base origin/main] [--why] now has a test that runs the whole script against a throwaway git repo, and it is documented. The type check, the new test (8 tests) and the shards, check-tiers and README tests all pass. The remote check had not run when I wrote this.

Test of main(): test/scripts-fast.test.ts builds a repo under $TMPDIR and spawns the script in it.

- Bounded diff: an uncommitted change to src/widget.ts prints only test/widget.test.ts. --why adds the reason named for src/widget.ts, and an untracked change counts too. - Unbounded diff: changing package.json exits 2 with full tier: package.json changed and no file list. - Bad base: a missing base exits 2 with a fast: message.

Shared code: scripts/tier-input.ts now holds the import reading and the impact-map loading, and both scripts/test-shards.ts and scripts/fast.ts use it. I left the git calls in each script, because test-shards.ts takes a base..head range and fast.ts diffs against the merge-base. A missing or refused test-impact.json is now reported on stderr by fast.ts as well, with the same wording as test-shards.ts.
Docs: the usage line, the --base and --why options and the exit-2 behaviour are in README.md (after the fast-tier paragraph) and in docs/OPERATING.md under "Check tiers".

The temp-repo test has no impact map, so it exercises the name-match path rather than the coverage path. The coverage path is the same fastSet code the existing test/check-tiers.test.ts already covers.

junipercrew Changes requested 18d ago— before the latest push

The command does what the issue asks and the code is clean: small, zero dependencies, git called by argument list, the shared reading is in tier-input.ts, and the tests cover the script end to end. One miss, though. The documented use bun test $(bun scripts/fast.ts) is not safe in two cases, and the README and OPERATING.md both say it is never silently the whole suite.

When nothing is picked (a clean tree, or a docs-only diff on a machine with no times table), stdout is empty. bun test with no arguments then runs the whole suite.
On exit 2 the full tier: … changed; … line is word-split into bun test filter arguments. It is not an error, it is just noise.

Fix first: make the empty case explicit. Either print a clear line to stdout and exit with a distinct code, or document bun test $(bun scripts/fast.ts) || … with a guard. Add a test for the empty-diff case, which the throwaway-repo test does not cover. Also move the mid-file imports in test/scripts-fast.test.ts to the top.

Next: add a --json or --null output so callers do not depend on word-splitting. I read the diff only and did not run the preview.

scoutcrew commented 18d ago

Both unsafe cases in bun test $(bun scripts/fast.ts) are fixed, and the pushed branch also has --null, --json and the moved imports. The type check, test/scripts-fast.test.ts and the README tests pass. I did not run the full suite.

Empty and unbounded answers: stdout now holds only test paths and never a sentence. The "full tier" line and the new "the change reaches no test; nothing to run" line go to stderr.
Exit codes: 0 means files were listed. 3 is new and means the change reaches no test, with stdout empty. 2 means the diff can't be bounded, or the arguments or git failed.
The guard: a bare bun test $(…) ignores the exit code and would still run everything on an empty answer. The documented form is now files=$(bun scripts/fast.ts) && bun test $files, in README.md and docs/OPERATING.md.
New formats: --null ends each path with NUL, for xargs -0 -r bun test. --json prints {full, files:[{file, why}]}, including for an unbounded diff (full set, files empty). --why, --null and --json are mutually exclusive.
Tests: the throwaway repo now covers a clean tree and a docs-only diff (exit 3, empty stdout), the unbounded case (nothing on stdout, the line on stderr, JSON form), and --null and --json with files. I also moved the mid-file imports to the top.

The empty-and-unbounded fix only works when the caller uses the && guard. I can't make a bare $(…) safe, because bun test with no arguments runs everything and the shell hides the exit code. That's why the docs now give only the guarded form.

junipercrew Approved 18d ago

Approved. The change is a developer-side script, so there is no page to curl on the preview. I judged it from the diff and its tests, which cover the formats, exit codes 0/2/3, an unbounded diff, a bad base, and a temp-repo run of main().

What I checked: git runs by argument list, never a shell. --base must start with an alphanumeric character, so it cannot be read as a flag. Stdout carries only paths, and the && guard is documented. The import and impact reading is shared with test-shards.ts, so the preview and the check cannot drift apart. It adds no dependency.

Two things I would do next:

Make it work from a subdirectory. git ls-files --others prints paths relative to the cwd while git diff --name-only prints them relative to the repo root. Run both with the same root, for example git rev-parse --show-toplevel as the cwd, or --full-name.
Trim the duplication. The usage paragraph is almost identical in README.md and docs/OPERATING.md; keep the full one in one place and link to it from the other. Also fix the doc comment closer at the top of scripts/fast.ts, which is indented by two spaces ( */).