1e3347fb46
Adds `cargo llvm-cov` to the devshell and a coverage workflow that runs only when someone asks for it. Manual dispatch rather than nightly or per-PR, per the discussion on the issue: a coverage run needs its own instrumented build and cannot reuse the normal test artifacts, so it roughly doubles a test job. "Do we have glaring holes" is a question someone asks occasionally, not a gate every PR pays for, and not a number worth spending farm time on every night whether or not anyone reads it. Manual dispatch costs nothing until the answer is wanted. Its own workflow file rather than a job in ci.yml: that file already has a `workflow_dispatch` trigger so `hive-forge ci-rerun` can retrigger without an empty commit, and a trigger there fires EVERY job in the file -- a coverage job added there would run on every pull request. No threshold and no --fail-under-lines. A coverage gate mostly teaches people to write assertion-free tests that execute lines; the report is the deliverable and the number is for a human to read. The devshell needs LLVM_COV / LLVM_PROFDATA set explicitly: cargo llvm-cov expects rustup's `llvm-tools-preview` beside the toolchain and nixpkgs has no such component, so without them it aborts with "failed to find llvm-tools-preview" -- which reads like a missing install rather than a path the shell has to name. Verified by running it: `cargo llvm-cov --package hive-types` produces a real report (3 tests, 85.44% regions). Both the variable names and the package were wrong on the first attempt and only running it said so -- the names take no `_PATH` suffix, and the binaries are in `llvmPackages.llvm`, not `llvmPackages.bintools`, which is the linker wrapper and ships neither.
40 lines
1.7 KiB
YAML
40 lines
1.7 KiB
YAML
name: coverage
|
|
|
|
# Manual dispatch ONLY — deliberately not on `pull_request`, and
|
|
# deliberately not nightly.
|
|
#
|
|
# A coverage run needs its own instrumented build: it cannot reuse the
|
|
# normal test artifacts, so it roughly doubles a test job. Coverage here
|
|
# answers "do we have glaring holes", which is a question someone asks
|
|
# occasionally — not a gate every PR pays for, and not a number worth
|
|
# spending farm time on every night whether or not anyone reads it.
|
|
# Manual dispatch costs nothing until someone wants the answer.
|
|
#
|
|
# Its own file rather than a job in ci.yml: that workflow already has a
|
|
# `workflow_dispatch` trigger (so `hive-forge ci-rerun` can retrigger
|
|
# without an empty commit), and a trigger there fires EVERY job in the
|
|
# file. A coverage job added to ci.yml would run on every pull request.
|
|
on:
|
|
workflow_dispatch:
|
|
|
|
jobs:
|
|
coverage:
|
|
name: cargo llvm-cov
|
|
runs-on: [hive-ci]
|
|
# Above the 30 min `nix flake check` allows, because instrumented
|
|
# builds are slower than the ordinary ones and this starts from a
|
|
# cache that the normal jobs never populate.
|
|
timeout-minutes: 60
|
|
steps:
|
|
- uses: actions/checkout@v3
|
|
- name: coverage
|
|
# No threshold and no `--fail-under-lines`: a coverage gate
|
|
# mostly teaches people to write assertion-free tests that
|
|
# execute lines. The report is the deliverable; the number is
|
|
# for a human to look at.
|
|
#
|
|
# `--workspace` because the interesting holes are in the crates
|
|
# nobody runs directly, and the per-crate default would hide
|
|
# exactly those behind a green summary for the one crate someone
|
|
# happened to name.
|
|
run: nix develop -c cargo llvm-cov --workspace --summary-only
|