return Scaffold(
  appBar: AppBar(title: Text("My app")),
  body: Column(
    children: [
      if (listTest.isEmpty) Center(child: Text("No items found.")),
      if (listTest.isNotEmpty)
        ListView.builder(
          padding: EdgeInsets.zero,
          shrinkWrap: true,
          itemCount: listTest.length,
          itemBuilder: (context, index) {
            return Padding(
              padding: const EdgeInsets.symmetric(horizontal: 15, vertical: 5),
              child: Card(
                elevation: 0,
                child: Padding(
                  padding: const EdgeInsets.all(1.0),
                  child: ListTile(
                    title: Text(listTest[index], maxLines: 1, overflow: TextOverflow.ellipsis),
                  ),
                ),
              ),
            );
          },
        ),
    ],
  ),
  floatingActionButton: FloatingActionButton(
    onPressed: addItem,
    tooltip: 'ADD',
    child: const Icon(Icons.add),
  ),
);

return Scaffold(
  appBar: AppBar(title: Text("My app")),
  body: ListView.builder(
    padding: EdgeInsets.zero,
    shrinkWrap: true,
    itemCount: listTest.length,
    itemBuilder: (context, index) {
      return Padding(
        padding: const EdgeInsets.symmetric(horizontal: 15, vertical: 5),
        child: Card(
          elevation: 0,
          child: Padding(
            padding: const EdgeInsets.all(1.0),
            child: ListTile(
              title: Text(listTest[index], maxLines: 1, overflow: TextOverflow.ellipsis),
            ),
          ),
        ),
      );
    },
    emptyBuilder: (context) {
      return SizedBox(
        height: MediaQuery.of(context).size.height,
        child: Center(child: Text("No items found.")),
      );
    },
  ),
  floatingActionButton: FloatingActionButton(
    onPressed: addItem,
    tooltip: 'ADD',
    child: const Icon(Icons.add),
  ),
);