CI tests

Author: andrjohns

.github/workflows/builds.yaml

@@ -0,0 +1,62 @@
+name: Build and Test CmdStan
+
+on:
+  pull_request:
+    branches: [ develop, master ]
+  push:
+    branches: [ develop, workflow-test ]
+permissions:
+  contents: read
+concurrency:
+  group: ${{ github.workflow }}-${{ github.head_ref || github.run_id }}
+  cancel-in-progress: true
+
+jobs:
+  prim-rev:
+    name: ${{ matrix.os }} tests
+    runs-on: ${{ matrix.os }}
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [
+          windows-11-arm,
+          windows-latest,
+          ubuntu-24.04-arm,
+          ubuntu-latest,
+          macos-latest,
+          macos-13
+        ]
+
+    steps:
+    - uses: actions/checkout@v4
+    - uses: actions/setup-python@v5
+      with:
+        python-version: '3.x'
+
+    - name: Download and Install Rtools45
+      if: runner.os == 'Windows'
+      run: |
+        $ARCH = if ('${{ matrix.os }}' -eq 'windows-11-arm') { 'aarch64' } else { 'x86_64' }
+        $RTOOLS = if ('${{ matrix.os }}' -eq 'windows-11-arm') { "rtools45-$ARCH" } else { 'rtools45' }
+
+        # Installation will hang if the toolchain is already installed
+        if (-Not $(Test-Path -Path "C:/$RTOOLS")) {
+          Invoke-WebRequest `
+              -Uri https://github.com/r-hub/rtools45/releases/download/latest/$RTOOLS.exe `
+              -OutFile "$RTOOLS.exe"
+          Start-Process -FilePath "$RTOOLS.exe" -ArgumentList "/INSTALL /VERYSILENT /SUPPRESSMSGBOXES" -Wait
+        }
+
+        echo "C:/$RTOOLS/usr/bin;C:/$RTOOLS/$ARCH-w64-mingw32.static.posix/bin" | Out-File -Append -FilePath $env:GITHUB_PATH -Encoding utf8
+        echo "$(pwd)/lib/tbb" | Out-File -Append -FilePath $env:GITHUB_PATH -Encoding utf8
+
+    - name: Build  libs
+      run: |
+        echo "CPPFLAGS=-w -Wno-psabi -Wno-misleading-indentation\n" >> make\local
+        echo "STAN_THREADS=true\n" >> make\local
+        make -j2 build
+
+    - name: Run unit tests
+      shell: pwsh
+      run: |
+        python runCmdStanTests.py -j2 src/test/interface