CI: Run a single job on Julia nightly

Author: DilumAluthge

.github/workflows/ci.nightly.yml

@@ -0,0 +1,54 @@
+name: Nightly CI
+
+on:
+  pull_request:
+  push:
+    branches:
+      - 'master'
+      - 'release-*'
+    tags: '*'
+  merge_group: # GitHub Merge Queue
+
+concurrency:
+  # Skip intermediate builds: all builds except for builds on the `master` branch
+  # Cancel intermediate builds: only pull request builds
+  group: ${{ github.workflow }}-${{ github.ref }}-${{ github.ref != 'refs/heads/master' || github.run_number }}
+  cancel-in-progress: ${{ startsWith(github.ref, 'refs/pull/') }}
+
+jobs:
+  test-nightly:
+    timeout-minutes: 90
+    runs-on: ${{ matrix.github-runner }}
+    strategy:
+      max-parallel: 5 # leave space for other runs in the JuliaLang org, given these tests are long
+      fail-fast: false
+      matrix:
+        include:
+          # We intentionally only run one CI job on Julia nightly,
+          # in order to conserve CI resources.
+          - julia-version: 'nightly'
+            julia-wordsize: '64'
+            github-runner: ubuntu-latest
+            coverage: false
+    steps:
+      - uses: actions/checkout@eef61447b9ff4aafe5dcd4e0bbf5d482be7e7871 # v4.2.1
+      - uses: julia-actions/setup-julia@9b79636afcfb07ab02c256cede01fe2db6ba808c # v2.6.0
+        with:
+          version: ${{ matrix.julia-version }}
+          # If `julia-wordsize` is 32, then we set `arch` to `x86`, because we know that
+          # 32-bit builds of Julia are only available for x86.
+          #
+          # If `julia-wordsize` is 64, then we set `arch` to `${{ runner.arch }}`, which
+          # GitHub will automatically expand to the correct value (`x86_64` or `aarch64`)
+          # based on the architecture of the underlying GitHub Runner (virtual machine).
+          arch: ${{ github.ref == '32' && 'x86' || runner.arch }}
+      - uses: julia-actions/cache@824243901fb567ccb490b0d0e2483ccecde46834 # v2.0.5
+      - uses: julia-actions/julia-runtest@d0c4f093badade621cd041bba567d1e832480ac2 # v1.10.0
+        with:
+          coverage: ${{ matrix.coverage }}
+      - uses: julia-actions/julia-processcoverage@03114f09f119417c3242a9fb6e0b722676aedf38 # v1.2.2
+      - uses: codecov/codecov-action@b9fd7d16f6d7d1b5d2bec1a2887e65ceed900238 # v4.6.0
+        with:
+          file: lcov.info
+        env:
+          CODECOV_TOKEN: ${{ secrets.CODECOV_TOKEN }}