Add integration test for GitHub Actions CI patterns (#3805)

.github/workflows/ci.yml

@@ -468,6 +468,39 @@ jobs:
           echo "$CONDA_PREFIX"
           ./uv pip install anyio
 
+  integration-test-github-actions:
+    needs: build-binary-linux
+    name: "integration test | github actions"
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-python@v5
+        with:
+          python-version: "3.12"
+
+      - name: "Download binary"
+        uses: actions/download-artifact@v4
+        with:
+          name: uv-linux-${{ github.sha }}
+
+      - name: "Prepare binary"
+        run: chmod +x ./uv
+
+      - name: "Install a package without system opt-in"
+        run: |
+          ./uv pip install anyio && exit 1 || echo "Failed as expected"
+
+      - name: "Install a package with system opt-in"
+        run: |
+          ./uv pip install anyio --system
+
+      - name: Configure uv to use the system Python by default
+        run: echo "UV_SYSTEM_PYTHON=1" >> $GITHUB_ENV
+
+      - name: "Install a package with environment system opt-in"
+        run: |
+          ./uv pip install anyio --reinstall
+
   cache-test-ubuntu:
     needs: build-binary-linux
     name: "check cache | ubuntu"