Move JET into a separate QA test group (#135)

PR #133's CI fails on Julia pre (1.13.0-beta3) at the Pkg.resolve step:
JET 0.11.3 (its current max release) has no version compatible with Julia
1.13, so the entire main test environment cannot be instantiated. JET is a
quality-assurance tool, not a runtime dependency, so blocking the main test
matrix on its release cadence is the wrong tradeoff.

Move JET to a dedicated QA group, mirroring how SciML/Sundials.jl ships
JET/Aqua/ExplicitImports — `test/qa/` has its own `Project.toml` and
`runtests.jl`, activated explicitly by a separate `QA.yml` workflow. The
main `Tests.yml` matrix no longer installs JET and so resolves cleanly on
Julia pre.

Changes:
- Add `test/qa/Project.toml` (deps: JET, MultiScaleArrays, Test) and
  `test/qa/runtests.jl` (runs `JET.report_package`, asserts zero reports).
- Delete `test/jet_tests.jl` and remove the corresponding `@testset` from
  `test/runtests.jl`.
- Drop `JET` from main `Project.toml` `[compat]`, `[extras]`, and the
  `test` target.
- Add `.github/workflows/QA.yml` that runs `test/qa/runtests.jl` on Julia
  `1` and `lts` (skips `pre` since JET has no Julia 1.13 release yet).

Verified locally on Julia 1.12.6:
- `julia --project=test/qa test/qa/runtests.jl` -> Quality Assurance | 1 1 11.5s.
- `julia --project=. -e 'using Pkg; Pkg.test()'` (main suite, no JET):
  Tuple Nodes / Bisect Search / Indexing and Creation / Values Indexing /
  Get Indices / Additional Fields / Dynamic DiffEq / Single Layer DiffEq /
  New Nodes — all pass; "Testing MultiScaleArrays tests passed".

Co-authored-by: ChrisRackauckas-Claude <accounts@chrisrackauckas.com>

Author: ChrisRackauckas-Claude

.github/workflows/QA.yml

@@ -0,0 +1,42 @@
+name: "QA"
+
+on:
+  pull_request:
+    branches:
+      - master
+    paths-ignore:
+      - 'docs/**'
+  push:
+    branches:
+      - master
+    paths-ignore:
+      - 'docs/**'
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: ${{ github.ref_name != github.event.repository.default_branch || github.ref != 'refs/tags/v*' }}
+
+jobs:
+  qa:
+    name: "QA - Julia ${{ matrix.version }}"
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        version:
+          - "1"
+          - "lts"
+    steps:
+      - uses: actions/checkout@v6
+      - uses: julia-actions/setup-julia@v3
+        with:
+          version: ${{ matrix.version }}
+      - uses: julia-actions/cache@v3
+      - name: "Instantiate test/qa"
+        run: |
+          julia --project=test/qa -e '
+            using Pkg
+            Pkg.develop(path=".")
+            Pkg.instantiate()'
+      - name: "Run QA tests"
+        run: julia --project=test/qa test/qa/runtests.jl

Project.toml

@@ -31,7 +31,6 @@ DiffEqBase = "7"
 DifferentiationInterface = "0.7.7"
 FiniteDiff = "2.3"
 ForwardDiff = "0.10, 1.3"
-JET = "0.9, 0.10, 0.11"
 OrdinaryDiffEq = "7"
 OrdinaryDiffEqCore = "4"
 OrdinaryDiffEqDifferentiation = "3"
@@ -45,10 +44,9 @@ julia = "1.10"
 
 [extras]
 ADTypes = "47edcb42-4c32-4615-8424-f2b9edc5f35b"
-JET = "c3a54625-cd67-489e-a8e7-0a5a0ff4e31b"
 OrdinaryDiffEq = "1dea7af3-3e70-54e6-95c3-0bf5283fa5ed"
 SafeTestsets = "1bc83da4-3b8d-516f-aca4-4fe02f6d838f"
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
 
 [targets]
-test = ["ADTypes", "JET", "OrdinaryDiffEq", "SafeTestsets", "Test"]
+test = ["ADTypes", "OrdinaryDiffEq", "SafeTestsets", "Test"]

test/jet_tests.jl

@@ -0,0 +1,7 @@
+[deps]
+JET = "c3a54625-cd67-489e-a8e7-0a5a0ff4e31b"
+MultiScaleArrays = "f9640e96-87f6-5992-9c3b-0743c6a49ffa"
+Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
+
+[compat]
+JET = "0.9, 0.10, 0.11"

test/qa/Project.toml

@@ -0,0 +1,13 @@
+using JET
+using MultiScaleArrays
+using Test
+
+@testset "Quality Assurance" begin
+    @testset "JET static analysis" begin
+        report = JET.report_package(
+            MultiScaleArrays;
+            target_modules = (MultiScaleArrays,)
+        )
+        @test length(JET.get_reports(report)) == 0
+    end
+end

test/qa/runtests.jl

@@ -1,9 +1,6 @@
 using MultiScaleArrays, OrdinaryDiffEq, DiffEqBase, StochasticDiffEq, SafeTestsets
 using Test
 
-@time @testset "JET Static Analysis" begin
-    include("jet_tests.jl")
-end
 @time @testset "Tuple Nodes" begin
     include("tuple_nodes.jl")
 end