[desktop-lite] - add tests for running xtigervnc and novnc (#1090)

* [desktop-lite] - add tests for running xtigervnc and novnc

* change for error while running test scenario

* changed test

* Update devcontainer-feature.json

---------
Co-authored-by: Samruddhi Khandale <samruddhikhandale@github.com>

src/desktop-lite/devcontainer-feature.json

 {
     "id": "desktop-lite",
-    "version": "1.2.3",
+    "version": "1.2.4",
     "name": "Light-weight Desktop",
     "documentationURL": "https://github.com/devcontainers/features/tree/main/src/desktop-lite",
     "description": "Adds a lightweight Fluxbox based desktop to the container that can be accessed using a VNC viewer or the web. GUI-based commands executed from the built-in VS code terminal will open on the desktop automatically.",

src/desktop-lite/install.sh

@@ -394,8 +394,12 @@ else
 fi
 
 # Run whatever was passed in
-log "Executing \"\$@\"."
-exec "$@"
+if [ -n "$1" ]; then
+    log "Executing \"\$@\"."
+    exec "$@"
+else
+    log "No command provided to execute."
+fi
 log "** SCRIPT EXIT **"
 EOF
 

test/desktop-lite/scenarios.json

+{
+    "test_xtigervnc_novnc_started": {
+        "image": "ubuntu:noble",
+        "features": {
+            "desktop-lite": {}
+        }
+    }
+}
\ No newline at end of file

test/desktop-lite/test_xtigervnc_novnc_started.sh

+#!/bin/bash
+
+set -e
+
+# Optional: Import test library
+source dev-container-features-test-lib
+
+# Check if xtigervnc & noVnc processes are running after successful installation and initialization
+check_process_running() {
+    port=$1
+    # Get process id of process running on specific port
+    PID=$(lsof -i :$port | awk 'NR==2 {print $2}')
+    if [ -n "$PID" ]; then
+        CMD=$(ps -p $PID -o cmd --no-headers)
+        GREEN='\033[0;32m'; NC='\033[0m'; RED='\033[0;31m'; YELLOW='\033[0;33m';
+        echo -e "${GREEN}Command running on port $port: ${YELLOW}$CMD${NC}"
+    else
+        echo -e "${RED}No process found listening on port $port.${NC}"
+    fi
+}
+
+check "Whether xtigervnc is Running" check_process_running 5901
+sleep 1
+check "Whether no_vnc is Running" check_process_running 6080
+
+check "desktop-init-exists" bash -c "ls /usr/local/share/desktop-init.sh"
+check "log-exists" bash -c "ls /tmp/container-init.log"
+check "log file contents" bash -c "cat /tmp/container-init.log"
+
+# Report result
+reportResults
\ No newline at end of file