added Semantics label to TextField with InputDecoration to let user k… (flutter#151996)

Semantics label to TextField with InputDecoration to let user know about
existing suffix

Before: https://screenshot.googleplex.com/3U9QyZ6Pqx2xeCf
After: https://screenshot.googleplex.com/73BSKQJhssGCoZu

fixes b/341998411
fixes b/342002217

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responsibilities.
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we expect every widget to implement].
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- [x] I listed at least one issue that this PR fixes in the description
above.
- [x] I updated/added relevant documentation (doc comments with `///`).
- [x] I added new tests to check the change I am making, or this PR is
[test-exempt].
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Author: DBowen33

dev/a11y_assessments/lib/use_cases/text_field.dart

@@ -30,25 +30,31 @@ class _MainWidget extends StatelessWidget {
       ),
       body: ListView(
         children: <Widget>[
-          const TextField(
-            key: Key('enabled text field'),
-            maxLines: null,
-            decoration: InputDecoration(
-              labelText: 'Email',
-              suffixText: '@gmail.com',
-              hintText: 'Enter your email',
+          Semantics(
+            label: 'Input field with suffix @gmail.com',
+            child: const TextField(
+              key: Key('enabled text field'),
+              maxLines: null,
+              decoration: InputDecoration(
+                labelText: 'Email',
+                suffixText: '@gmail.com',
+                hintText: 'Enter your email',
+              ),
             ),
           ),
-          TextField(
-            key: const Key('disabled text field'),
-            maxLines: null,
-            decoration: const InputDecoration(
-              labelText: 'Email',
-              suffixText: '@gmail.com',
-              hintText: 'Enter your email',
+          Semantics(
+            label: 'Input field with suffix @gmail.com',
+            child: TextField(
+              key: const Key('disabled text field'),
+              maxLines: null,
+              decoration: const InputDecoration(
+                labelText: 'Email',
+                suffixText: '@gmail.com',
+                hintText: 'Enter your email',
+              ),
+              enabled: false,
+              controller: TextEditingController(text: 'xyz'),
             ),
-            enabled: false,
-            controller: TextEditingController(text: 'xyz'),
           ),
         ],
       ),

dev/a11y_assessments/test/text_field_test.dart

@@ -54,4 +54,12 @@ void main() {
       expect(size.height, 280);
     }
   });
+
+  testWidgets('text field wrapper exists', (WidgetTester tester) async {
+    await pumpsUseCase(tester, TextFieldUseCase());
+    const String textFieldLabel = 'Input field with suffix @gmail.com';
+
+    final Finder semanticsWidgets = find.bySemanticsLabel(RegExp(textFieldLabel));
+    expect(semanticsWidgets, findsExactly(2));
+  });
 }