feat: add api test

Signed-off-by: Xinwei Xiong(cubxxw) <3293172751nss@gmail.com>

scripts/lib/util.sh

@@ -1126,6 +1126,21 @@ function openim::util::require-jq {
   fi
 }
 
+# openim::util::require-dig
+# Checks whether dig is installed and provides installation instructions if it is not.
+function openim::util::require-dig {
+  if ! command -v dig &>/dev/null; then
+    echo "dig command not found."
+    echo "Please install 'dig' to use this feature."
+    echo "Installation instructions:"
+    echo "  For Ubuntu/Debian: sudo apt-get install dnsutils"
+    echo "  For CentOS/RedHat: sudo yum install bind-utils"
+    echo "  For macOS: 'dig' should be preinstalled. If missing, try: brew install bind"
+    echo "  For Windows: Install BIND9 tools from https://www.isc.org/download/"
+    return 1
+  fi
+}
+
 # outputs md5 hash of $1, works on macOS and Linux
 function openim::util::md5() {
   if which md5 >/dev/null 2>&1; then