Fix capitalization in gallery RegExp (#12035)

examples/flutter_gallery/lib/demo/material/text_form_field_demo.dart

@@ -53,7 +53,7 @@ class TextFormFieldDemoState extends State<TextFormFieldDemo> {
     _formWasEdited = true;
     if (value.isEmpty)
       return 'Name is required.';
-    final RegExp nameExp = new RegExp(r'^[A-za-z ]+$');
+    final RegExp nameExp = new RegExp(r'^[A-Za-z ]+$');
     if (!nameExp.hasMatch(value))
       return 'Please enter only alphabetical characters.';
     return null;

examples/flutter_gallery/test/demo/material/text_form_field_demo_test.dart

+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/material.dart';
+import 'package:flutter_gallery/demo/material/text_form_field_demo.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+void main() {
+  testWidgets('validates name field correctly', (WidgetTester tester)  async {
+    await tester.pumpWidget(new MaterialApp(home: const TextFormFieldDemo()));
+
+    final Finder submitButton = find.widgetWithText(RaisedButton, 'SUBMIT');
+    expect(submitButton, findsOneWidget);
+
+    final Finder nameField = find.widgetWithText(TextFormField, 'Name *');
+    expect(nameField, findsOneWidget);
+
+    await tester.enterText(nameField, '');
+    await tester.tap(submitButton);
+    await tester.pump();
+    expect(find.text('Name is required.'), findsOneWidget);
+    expect(find.text('Please enter only alphabetical characters.'), findsNothing);
+
+    await tester.enterText(nameField, '#');
+    await tester.tap(submitButton);
+    await tester.pump();
+    expect(find.text('Name is required.'), findsNothing);
+    expect(find.text('Please enter only alphabetical characters.'), findsOneWidget);
+
+    await tester.enterText(nameField, 'Jane Doe');
+    await tester.tap(submitButton);
+    await tester.pump();
+    expect(find.text('Name is required.'), findsNothing);
+    expect(find.text('Please enter only alphabetical characters.'), findsNothing);
+  });
+}