Canonical CI: grouped-tests.yml + root test/test_groups.toml

[ChrisRackauckas-Claude]

Summary

Converts the root Tests.yml test workflow to the canonical thin caller using SciML/.github/.github/workflows/grouped-tests.yml@v1, with the group × version matrix declared once in a new root test/test_groups.toml.

Changes

• .github/workflows/Tests.yml — the matrix test job is replaced by the thin caller:

  jobs:
    tests:
      uses: "SciML/.github/.github/workflows/grouped-tests.yml@v1"
      secrets: "inherit"

  name: "Tests", the on: triggers, and concurrency: are preserved verbatim so branch-protection status checks are unaffected. No other workflow files were touched (Downgrade, Downstream, Documentation, FormatCheck, SpellCheck, TagBot, RunicSuggestions, DependabotAutoMerge, DocPreviewCleanup all left as-is).
• test/test_groups.toml (new):

  [Core]
  versions = ["lts", "1", "pre"]
  
  [QA]
  versions = ["lts", "1"]

Why no with: inputs

runtests.jl already dispatches on the standard GROUP env var (Core/QA), so the default group-env-name (GROUP) applies. The old caller invoked tests.yml@v1 with all defaults (check-bounds=yes, coverage=true, coverage-directories=src,ext, apt-packages=""), all of which match grouped-tests.yml's defaults — so the thin caller needs no with: block.

Matrix match: 5/5 exact

Old workflow matrix was version: [1, lts, pre] × group: [Core, QA] with exclude: pre × QA → 5 cells. Running compute_affected_sublibraries.jl <root> --root-matrix against the new test/test_groups.toml emits exactly:

• (Core, lts), (Core, 1), (Core, pre)
• (QA, lts), (QA, 1)

The QA-off-pre constraint (JET 0.11.x cannot resolve on Julia 1.13 prereleases) is preserved by declaring QA's versions = ["lts", "1"] rather than via a matrix exclude.

Verification

• Root-matrix script run with Julia 1.11: reproduces old matrix 5/5 exact.
• test/test_groups.toml parses (Julia TOML); Tests.yml parses (YAML).

QA findings

None. This is a CI-plumbing change only; runtests.jl already had Core/QA GROUP dispatch (QA = JET static analysis), so no source or test changes were made.

Ignore until reviewed by @ChrisRackauckas.