Run tests on 32-bit PHP

Author: BenMorel

.github/workflows/ci.yml

@@ -103,3 +103,41 @@ jobs:
         env:
           CODECOV_TOKEN: ${{ secrets.CODECOV_TOKEN }}
         if: ${{ matrix.php-version == env.COVERAGE_PHP_VERSION }}
+
+  phpunit-32bit:
+    name: PHPUnit (32-bit)
+    runs-on: ubuntu-latest
+    container:
+      image: php:8.5-cli
+      options: --platform linux/386
+
+    strategy:
+      fail-fast: false
+      matrix:
+        calculator:
+          - GMP
+          - BCMath
+          - Native
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Install dependencies
+        run: |
+          apt-get update
+          apt-get install -y libgmp-dev unzip
+          docker-php-ext-install gmp bcmath > /dev/null
+
+      - name: Install composer dependencies
+        uses: ramsey/composer-install@v3
+
+      - name: Ensure 32-bit
+        run: |
+          php -r 'echo "PHP_INT_SIZE=", PHP_INT_SIZE, "\n";'
+          php -r 'exit(PHP_INT_SIZE === 4 ? 0 : 1);'
+
+      - name: Run PHPUnit
+        run: vendor/bin/phpunit
+        env:
+          CALCULATOR: ${{ matrix.calculator }}