From 1195e9047650f7d4f27e2924864fe7e131f0a07d Mon Sep 17 00:00:00 2001 From: Joseph Ferano Date: Sun, 13 Sep 2026 23:25:48 +0700 Subject: [PATCH] The noise is gone and the reporting half is verified by breaking the test on purpose --- HANDOFF-devtest-noise.md | 50 ++++++++++++++++++++++++++++++++++------ 1 file changed, 43 insertions(+), 7 deletions(-) diff --git a/HANDOFF-devtest-noise.md b/HANDOFF-devtest-noise.md index 2cc0045..1d077ff 100644 --- a/HANDOFF-devtest-noise.md +++ b/HANDOFF-devtest-noise.md @@ -39,15 +39,51 @@ stderr was simply never given the same treatment. The result is four lines of what reads like a broken toolchain on a passing run. A real linker failure in that spot today would be invisible. -## The plan +## What was done -1. Give the robustness daemon its own stderr log rather than the suite's, the same way its stdout already has one. -2. Report that log — and say so — only when something in the block actually failed, so a genuine linker error is - still visible, and a deliberate one is not. -3. Have the fixture announce the deliberate failure in its own voice before it causes it, so a reader of the output - knows a build is about to be made to fail and why. +Three changes, all in `test/test_dev.ml` and all inside the `dev-robust` block. The lever that causes the failure +is untouched: the existing comment's argument that a read-only cache is "the one lever that reaches the macro module +and nothing else" is right, and swapping it for a different cause would mean re-proving that the new one does not +leak into other builds. The channel was the defect, not the cause. -Baseline to not regress: `dune test --root .` exit 0, `spike/x86/survey.sh` 101 MATCH / 0 DIFFER / 0 refused, +1. **The daemon gets a stderr of its own** — `rerr = tmp "robust.err"`, passed to `create_process_env` where + `Unix.stderr` used to be, the same treatment its stdout already had. +2. **That log is reprinted, contents and not path, only when a step in this block failed.** The count is taken + against `rfailures`, a snapshot of `!failures` at block entry, because `failures` is the whole file's and an + earlier block's failure is not a reason to reprint this daemon's expected complaints. The path itself would be + useless: `rerr` lives under dune's per-run `TMPDIR`, which is gone before anyone reads the run. +3. **The fixture says so in its own voice**, one line, before the daemon starts. The wording deliberately contains + no `error`, `Error` or `FAIL`, because the reader it is written for is scanning for exactly those words. + +## Measured, before and after + +Both from a full `dune test --root .`, exit 0 either way. + +| | before | after | +|---|---|---| +| `cannot open output file` lines | 2 | **0** | +| `clang: error: linker command failed` lines | 2 | **0** | +| a line saying the failure is deliberate | none | **1** | + +The two occurrences in the baseline were at `baseline.log:563` and `:565`, immediately after +`flan dev: ... dev-robust.flan ready on ...` — which places them in this block and nowhere else. **The count is +exactly two**, so there is no second site elsewhere in the suite quietly doing the same thing; fixing `test_dev.ml` +fixes all of it. + +Two informational lines from this daemon — `flan dev: built dev-robust.flan in 1937ms` and its `ready on` — now go +to the log with the rest of its stderr rather than to the terminal. Its siblings still print theirs. That is a small +inconsistency and the right side of the trade: the whole point is that this daemon's stderr is a channel nobody +should be reading on a green run. + +## Verified + +- `dune test --root .` exit 0, and the four lines are gone. `test_dev` alone: `dev: all tests passed`, exit 0. +- **The reporting half was verified by breaking the test on purpose**, which is the part a green run cannot show: + a fix that silences unconditionally and a fix that reports-on-failure produce identical output when everything + passes. The `Some "16"` expectation was temporarily changed to a value it cannot match, the block failed, and the + captured stderr — the linker's own words — was reprinted under its header. Then reverted. + +Baseline not regressed: `dune test --root .` exit 0, `spike/x86/survey.sh` 101 MATCH / 0 DIFFER / 0 refused, `spike/x86/cells.sh` 4/4. ## Open questions