Added test case scenario for Update-Alternatives check

test/python/update-alternatives_switchable_versions.sh

@@ -0,0 +1,59 @@
+#!/bin/bash
+
+set -e
+
+# Optional: Import test library
+source dev-container-features-test-lib
+
+check "python version 3.11 installed as default" bash -c "python --version | grep 3.11"
+check "python3 version 3.11 installed as default" bash -c "python3 --version | grep 3.11"
+check "python version 3.10.5 installed"  bash -c "ls -l /usr/local/python | grep 3.10.5"
+check "python version 3.8 installed"  bash -c "ls -l /usr/local/python | grep 3.8"
+check "python version 3.9.13 installed"  bash -c  "ls -l /usr/local/python | grep 3.9.13"
+
+# Check paths in settings
+check "current symlink is correct" bash -c "which python | grep /usr/local/python/current/bin/python"
+check "current symlink works" /usr/local/python/current/bin/python --version
+
+# check update-alternatives command
+
+check_version_switch() {
+    PYTHON_ALTERNATIVES=$(update-alternatives --query python3 | grep -E 'Alternative:|Priority:')
+    AVAILABLE_VERSIONS=()
+    INDEX=1
+
+    echo "Available Python versions:"
+    while read -r alt && read -r pri; do
+        PATH=${alt#Alternative: }   # Extract only the path
+        PRIORITY=${pri#Priority: }  # Extract only the priority number
+        AVAILABLE_VERSIONS+=("$PATH")
+        echo "$INDEX) $PATH (Priority: $PRIORITY)"
+        ((INDEX++))
+    done <<< "${PYTHON_ALTERNATIVES}"
+
+    echo -e "\n"
+
+    # Ensure at least 4 alternatives exist
+    if [ "${#AVAILABLE_VERSIONS[@]}" -lt 4 ]; then
+        echo "Error: Less than 4 Python versions registered in update-alternatives."
+        exit 1
+    fi
+
+    for CHOICE in {1..4}; do
+        SELECTED_VERSION="${AVAILABLE_VERSIONS[$((CHOICE - 1))]}"
+        echo "Switching to: ${SELECTED_VERSION}"
+        /usr/bin/update-alternatives --set python3 ${SELECTED_VERSION}
+
+        # Verify the switch
+        echo "Python version after switch:"
+        /usr/local/python/current/bin/python3 --version
+
+        /bin/sleep 2
+
+        echo -e "\n"
+    done
+    echo -e "Update-Alternatives --display: \n"
+    /usr/bin/update-alternatives --display python3
+}
+
+check "Version Switch With Update_Alternatives" check_version_switch