ci: add GitHub Actions workflow for runtime tests

Add automated runtime testing that runs on every push and pull request:
- Tests Slurm 24.11 on Ubuntu 25.04 (plucky)
- Uses Docker Buildx with GitHub Actions caching
- Runs full integration test suite with live Slurm cluster
- Validates plugin installation, job execution, and containerized workloads

Updates documentation and adds Runtime Tests badge to README.

Author: dennisklein

.github/workflows/runtime-tests.yml

@@ -0,0 +1,37 @@
+name: Runtime Tests
+
+on:
+  push:
+    branches: [ main ]
+  pull_request:
+    branches: [ main ]
+
+permissions:
+  contents: read
+
+jobs:
+  runtime-test:
+    name: Slurm ${{ matrix.slurm }}
+    runs-on: ubuntu-latest
+
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - ubuntu_version: plucky
+            slurm: 24.11
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Run runtime integration tests
+        run: |
+          cd tests/runtime
+          UBUNTU_VERSION=${{ matrix.ubuntu_version }} ./run-tests.sh
+        env:
+          UBUNTU_VERSION: ${{ matrix.ubuntu_version }}
+          BUILDX_CACHE_FROM: type=gha,scope=${{ matrix.ubuntu_version }}
+          BUILDX_CACHE_TO: type=gha,mode=max,scope=${{ matrix.ubuntu_version }}

README.md

@@ -1,6 +1,6 @@
 # Slurm Singularity SPANK Plugin
 
-[![Build](https://github.com/GSI-HPC/slurm-singularity-exec/actions/workflows/build.yml/badge.svg)](https://github.com/GSI-HPC/slurm-singularity-exec/actions/workflows/build.yml) [![DOI](https://zenodo.org/badge/DOI/10.5281/zenodo.10719223.svg)](https://doi.org/10.5281/zenodo.10719223)
+[![Build](https://github.com/GSI-HPC/slurm-singularity-exec/actions/workflows/build.yml/badge.svg)](https://github.com/GSI-HPC/slurm-singularity-exec/actions/workflows/build.yml) [![Runtime Tests](https://github.com/GSI-HPC/slurm-singularity-exec/actions/workflows/runtime-tests.yml/badge.svg)](https://github.com/GSI-HPC/slurm-singularity-exec/actions/workflows/runtime-tests.yml) [![DOI](https://zenodo.org/badge/DOI/10.5281/zenodo.10719223.svg)](https://doi.org/10.5281/zenodo.10719223)
 
 The Singularity SPANK plugin provides the users with an interface to launch an
 application within a Linux container. The plug-in adds multiple command-line

tests/README.md

@@ -46,11 +46,26 @@ bats test_wrapper.bats
 - Error handling (missing files, invalid paths, special characters)
 - Command construction (argument ordering, bind mount syntax, environment propagation)
 
+## Runtime Integration Tests
+
+Runtime tests verify the plugin works with actual Slurm daemons:
+
+```bash
+cd tests/runtime
+./run-tests.sh
+```
+
+See [runtime/README.md](runtime/README.md) for detailed documentation on the Docker Compose architecture, test flow, and troubleshooting.
+
 ## Continuous Integration
 
-GitHub Actions tests on every push/PR with:
-- Slurm 23.11 (Ubuntu 24.04 Noble)
-- Slurm 24.11 (Ubuntu 25.04 Plucky)
+GitHub Actions runs tests on every push/PR:
+
+| Test Type | Slurm Version | Ubuntu Version | Description |
+|-----------|---------------|----------------|-------------|
+| Build | 23.11 | 24.04 Noble | Compile-time compatibility check |
+| Build | 24.11 | 25.04 Plucky | Compile-time compatibility check |
+| Runtime | 24.11 | 25.04 Plucky | Full integration tests with live cluster |
 
 ## Writing Tests