Add chromium fallback browser for e2e screenshot capture

Install chromium in the Docker container alongside google-chrome-stable.
Update screenshot.sh to try google-chrome-stable, chromium, and
chromium-browser in order, with screenshot size validation.

Author: guysoft

testing/Dockerfile

@@ -3,7 +3,7 @@ FROM ptrsr/pi-ci:latest
 ENV LIBGUESTFS_BACKEND=direct
 
 RUN apt-get update && apt-get install -y --no-install-recommends \
-    sshpass openssh-client curl socat imagemagick wget gnupg \
+    sshpass openssh-client curl socat imagemagick wget gnupg chromium \
     && wget -q -O - https://dl.google.com/linux/linux_signing_key.pub | gpg --dearmor -o /usr/share/keyrings/google-chrome.gpg \
     && echo "deb [arch=amd64 signed-by=/usr/share/keyrings/google-chrome.gpg] http://dl.google.com/linux/chrome/deb/ stable main" > /etc/apt/sources.list.d/google-chrome.list \
     && apt-get update && apt-get install -y --no-install-recommends google-chrome-stable \

testing/hooks/screenshot.sh

@@ -30,21 +30,34 @@ if [ "$WIZARD_READY" -eq 0 ]; then
 fi
 
 HTTP_PORT="${QEMU_HTTP_PORT:-8080}"
-BROWSER_PATH=$(command -v google-chrome-stable 2>/dev/null || true)
+SCREENSHOT_TAKEN=0
+
+for BROWSER in google-chrome-stable chromium chromium-browser; do
+    BROWSER_PATH=$(command -v "$BROWSER" 2>/dev/null || true)
+    [ -n "$BROWSER_PATH" ] || continue
 
-if [ -n "$BROWSER_PATH" ]; then
     echo "  Taking headless screenshot with $BROWSER_PATH ..."
-    timeout 30 "$BROWSER_PATH" --headless=new --no-sandbox --disable-gpu \
+    timeout 30 "$BROWSER_PATH" --headless --no-sandbox --disable-gpu \
         --disable-dev-shm-usage --virtual-time-budget=15000 \
         --screenshot="$ARTIFACTS_DIR/screenshot.png" \
         --window-size=1280,720 \
-        "http://localhost:${HTTP_PORT}" 2>&1 | tail -5 || true
+        "http://localhost:${HTTP_PORT}" 2>/dev/null || true
+
     if [ -f "$ARTIFACTS_DIR/screenshot.png" ]; then
         SIZE=$(stat -c%s "$ARTIFACTS_DIR/screenshot.png" 2>/dev/null || echo "0")
-        echo "  Screenshot saved (${SIZE} bytes)"
+        if [ "$SIZE" -gt 10000 ]; then
+            echo "  Screenshot saved (${SIZE} bytes) -- wizard page captured"
+            SCREENSHOT_TAKEN=1
+            break
+        else
+            echo "  WARNING: Screenshot is only ${SIZE} bytes (may be blank), trying next browser"
+            rm -f "$ARTIFACTS_DIR/screenshot.png"
+        fi
     else
-        echo "  Screenshot file was NOT created"
+        echo "  Screenshot file was NOT created by $BROWSER, trying next browser"
     fi
-else
-    echo "  No google-chrome-stable found in container"
+done
+
+if [ "$SCREENSHOT_TAKEN" -eq 0 ]; then
+    echo "  WARNING: No browser produced a valid screenshot"
 fi