Widget testing TestFailure on version 5.0.0-release-candidate-9.2.1

[feriyalsusanto]

Widget testing using latest version 5.0.0-release-candidate-9.2.1 always not found

test_page.dart

import 'package:flutter/material.dart';

class TestPage extends StatefulWidget {
  const TestPage({super.key});

  @override
  State<TestPage> createState() => _TestPageState();
}

class _TestPageState extends State<TestPage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('Test Page')),
      body: Padding(
        padding: const EdgeInsets.all(16),
        child: Column(
          children: [TextButton(key: const ValueKey('btn_submit'),
            onPressed: () {}, child: const Text('SUBMIT'))],
        ),
      ),
    );
  }
}

widget_test.dart

import 'package:flutter/material.dart';
import 'package:flutter_test/flutter_test.dart';
import 'package:get/get_navigation/src/root/get_material_app.dart';
import 'package:test_app/test_page.dart';

void main() {
  testWidgets('Find Button in Test Page', (WidgetTester tester) async {
    await tester.pumpWidget(const GetMaterialApp(home: TestPage()));

    var button = find.byKey(const ValueKey('btn_submit'));
    expect(button, findsOneWidget);
  });
}

Result

00:07 +0: Find Button in Test Page
══╡ EXCEPTION CAUGHT BY FLUTTER TEST FRAMEWORK ╞════════════════════════════════════════════════════
The following TestFailure was thrown running a test:
Expected: exactly one matching candidate
  Actual: _KeyWidgetFinder:<Found 0 widgets with key [<'btn_submit'>]: []>
   Which: means none were found but one was expected

When the exception was thrown, this was the stack:
#4      main.<anonymous closure> (file:///D:/Workspace/Appium/test-app/test_app/test/widget_test.dart:18:5)
<asynchronous suspension>
#5      testWidgets.<anonymous closure>.<anonymous closure> (package:flutter_test/src/widget_tester.dart:189:15)
<asynchronous suspension>
#6      TestWidgetsFlutterBinding._runTestBody (package:flutter_test/src/binding.dart:1032:5)
<asynchronous suspension>
<asynchronous suspension>
(elided one frame from package:stack_trace)

This was caught by the test expectation on the following line:
  file:///D:/Workspace/Appium/test-app/test_app/test/widget_test.dart line 18
The test description was:
  Find Button in Test Page
════════════════════════════════════════════════════════════════════════════════════════════════════
00:07 +0 -1: Find Button in Test Page [E]
  Test failed. See exception logs above.
  The test description was: Find Button in Test Page

But, if I using version 4.6.6, the test is passed.