added test infrastructure based on docker/podman

* documentation added
* scripts to setup image and start container added

post_installation_script_test/01_create_image.sh

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+#!/bin/bash
+
+# Create test image from Dockerfile
+docker build -t mint-script-test -f Dockerfile .

post_installation_script_test/02_start_container_with_image.sh

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+#!/bin/bash
+
+# Start container with the test image (interactive shell)
+docker run -it --rm \
+  --cap-drop ALL --security-opt no-new-privileges --tmpfs /tmp:rw \
+  -v "$(pwd)/../post_installation_script/20251212_Nachinstallationsarbeiten_LC_Esslingen_XFCE_v8.sh":/workspace/script.sh:ro \
+  mint-script-test

post_installation_script_test/Dockerfile

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+FROM ubuntu:22.04
+
+# Minimal image for safe simulation of apt installs.
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    bash wget tar curl gnupg ca-certificates apt-utils apt coreutils file procps && \
+    apt-get clean && rm -rf /var/lib/apt/lists/*
+
+# sudo wrapper: simulate apt installs and avoid making changes to the image
+RUN cat > /usr/local/bin/sudo <<'EOF'
+#!/bin/sh
+# sudo wrapper for simulation:
+# - simulate installs with `apt-get -s install ...`
+# - run `apt-get update` quietly (needed so apt -s has metadata)
+# - otherwise echo the command (no-op)
+cmd="$1"
+arg2="${2:-}"
+if [ "$cmd" = "apt" ] || [ "$cmd" = "apt-get" ]; then
+  if [ "$arg2" = "install" ]; then
+    shift 2
+    echo "[sudo-wrapper] simulating: apt-get -s install $@"
+    apt-get -s install "$@"
+    exit $?
+  elif [ "$arg2" = "update" ]; then
+    # do not run update at runtime (may require extra privileges); simulate instead
+    echo "[sudo-wrapper] simulating: apt-get update (no-op in container)"
+    exit 0
+  else
+    echo "[sudo-wrapper] would run: $@"
+    exit 0
+  fi
+else
+  echo "[sudo-wrapper] would run: $@"
+  exit 0
+fi
+EOF
+RUN chmod +x /usr/local/bin/sudo
+
+ENV PATH=/usr/local/bin:$PATH
+
+WORKDIR /workspace
+ENTRYPOINT ["/bin/bash"]

post_installation_script_test/README.md

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+# Post-Installation Script Testing
+
+This directory contains everything needed to test the post-installation script in a safe, isolated container environment.
+
+## Contents
+
+- `Dockerfile` - Container image definition for testing
+- `01_create_image.sh` - script for creating container image locally
+- `02_start_container_with_image.sh` - script for starting container from created image
+
+## Purpose
+
+Provides a reproducible testing environment that allows:
+
+- Running the post-installation script without affecting the host system
+- Simulating `apt` installations (safe, no real package changes)
+- Testing script logic, prompts, and error handling
+- Validating syntax and tracing execution
+
+## Features
+
+The Dockerfile includes:
+
+- Ubuntu 22.04 base image
+- Simulated `sudo` wrapper that runs `apt-get -s install` (simulates installs without making changes)
+- Useful utilities: `bash`, `wget`, `tar`, `curl`, `gnupg`, `ca-certificates`, `file`, `procps`
+
+## Usage
+
+### Build the test image
+Run the prepared shell script to build the image
+
+```bash
+cd post_installation_script_test
+sh 01_create_image.sh
+```
+
+### Start a container for testing
+Run the prepared shell script start a new container for testing based in the 
+image and remove container after it is stopped. After container is started an interactive session is started into the container.
+
+```bash
+cd post_installation_script_test
+sh 02_start_container_with_image.sh
+```
+
+
+### Test the script file in the running container
+After container is started an interactive session was started in the container and the script can be started for testing
+
+```bash
+sh script.sh
+```
+
+## Security Notes
+
+- The script is mounted read-only (`:ro` flag) to prevent container from modifying host files
+- Container runs with reduced privileges (`--cap-drop ALL --security-opt no-new-privileges`)
+- The `sudo` wrapper simulates apt operations, so no packages are actually installed
+- Use `--tmpfs /tmp:rw` for any temporary writes inside the container