test form

covas_mobile/lib/main.dart

@@ -113,6 +113,8 @@ class _MyHomePageState extends State<MyHomePage> {
     });
   }
 
+  final _formKey = GlobalKey<FormState>();
+
   @override
   Widget build(BuildContext context) {
     // This method is rerun every time setState is called, for instance as done
@@ -147,6 +149,23 @@ class _MyHomePageState extends State<MyHomePage> {
           // horizontal).
           mainAxisAlignment: MainAxisAlignment.center,
           children: <Widget>[
+            Form(
+              key: _formKey,
+              child: Column(
+                children: <Widget>[
+                  // Add TextFormFields and ElevatedButton here.
+                  TextFormField(
+                    // The validator receives the text that the user has entered.
+                    validator: (value) {
+                      if (value == null || value.isEmpty) {
+                        return 'Please enter some text';
+                      }
+                      return null;
+                    },
+                  ),
+                ],
+              ),
+            ),
             const Text(
               'You have pushed the button this many times:',
             ),