Split Julia pre CI into separate workflow and add macOS ARM

Move the Julia pre release testing into its own workflow file (ci-pre.yml)
that runs only on ubuntu-latest. The pre workflow strips the JET dependency
from test/Project.toml via sed since JET often breaks on pre-release Julia.
Also add macOS ARM (aarch64) to the main CI matrix.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: Krastanov

.github/workflows/ci-pre.yml

@@ -0,0 +1,37 @@
+name: CI (Julia pre)
+env:
+  JULIA_NUM_THREADS: 2
+concurrency:
+  # group by workflow and ref; the last slightly strange component ensures that for pull
+  # requests, we limit to 1 concurrent job, but for the master branch we don't
+  group: ${{ github.workflow }}-${{ github.ref }}-${{ (github.ref != 'refs/heads/master' && github.ref != 'refs/heads/main') || github.run_number }}
+  # Cancel intermediate builds, but only if it is a pull request build.
+  cancel-in-progress: ${{ startsWith(github.ref, 'refs/pull/') }}
+on:
+  pull_request:
+    branches:
+      - master
+  push:
+    branches:
+      - master
+    tags: '*'
+jobs:
+  test:
+    name: Julia pre - ubuntu-latest - x64 - ${{ github.event_name }}
+    runs-on: ubuntu-latest
+    continue-on-error: true
+    steps:
+      - uses: actions/checkout@v6
+      - uses: julia-actions/setup-julia@v2
+        with:
+          version: pre
+      - uses: julia-actions/cache@v2
+      - run: sed -i '/JET/d' test/Project.toml
+      - uses: julia-actions/julia-buildpkg@v1
+      - uses: julia-actions/julia-runtest@v1
+      - uses: julia-actions/julia-processcoverage@v1
+      - uses: codecov/codecov-action@v5
+        with:
+          files: lcov.info
+          token: ${{ secrets.CODECOV_TOKEN }}
+          fail_ci_if_error: false

.github/workflows/ci.yml

@@ -25,13 +25,16 @@ jobs:
         version:
           - '1'
           - '1.10'
-          - 'pre'
         os:
           - ubuntu-latest
           - macos-latest
           - windows-latest
         arch:
           - x64
+        include:
+          - version: '1'
+            os: macos-latest
+            arch: aarch64
     steps:
       - uses: actions/checkout@v6
       - uses: julia-actions/setup-julia@v2

test/runtests.jl

@@ -3,7 +3,9 @@ using Documenter
 using Graphs
 using Graphs.SimpleGraphs
 using Graphs.Experimental
-using JET
+if isempty(VERSION.prerelease)
+    using JET
+end
 using Graphs.Test
 using Test
 using SparseArrays
@@ -154,14 +156,16 @@ tests = [
 ]
 
 @testset verbose = true "Graphs" begin
-    @testset "Code quality (JET.jl)" begin
-        @assert get_pkg_version("JET") >= v"0.8.4"
-        JET.test_package(
-            Graphs;
-            target_defined_modules=true,
-            ignore_missing_comparison=true,
-            mode=:typo,  # TODO: switch back to `:basic` once the union split caused by traits is fixed
-        )
+    if isempty(VERSION.prerelease)
+        @testset "Code quality (JET.jl)" begin
+            @assert get_pkg_version("JET") >= v"0.8.4"
+            JET.test_package(
+                Graphs;
+                target_defined_modules=true,
+                ignore_missing_comparison=true,
+                mode=:typo,  # TODO: switch back to `:basic` once the union split caused by traits is fixed
+            )
+        end
     end
 
     @testset "Code quality (Aqua.jl)" begin