fix: Dialog and dropdown are no longer visible on the golden files (B…

…etterment#79)

lib/src/golden_test_adapter.dart

@@ -136,6 +136,9 @@ abstract class GoldenTestAdapter {
 
   /// Pumps the given [widget] with the given [tester] for use in golden tests.
   ///
+  /// The [rootKey], if provided, will be attached to the top-most [Widget] in
+  /// the tree.
+  ///
   /// The [textScaleFactor], if provided, sets the text scale size (usually in
   /// a range from 1 to 3).
   ///
@@ -154,6 +157,7 @@ abstract class GoldenTestAdapter {
   /// max width is unbounded, a default width value will be used as initial
   /// surface size. The same applies to the max height.
   Future<void> pumpGoldenTest({
+    Key? rootKey,
     required WidgetTester tester,
     required double textScaleFactor,
     required BoxConstraints constraints,
@@ -181,6 +185,9 @@ class FlutterGoldenTestAdapter extends GoldenTestAdapter {
   /// Create a new [FlutterGoldenTestAdapter].
   const FlutterGoldenTestAdapter() : super();
 
+  /// Key for the root of the golden test.
+  static final rootKey = UniqueKey();
+
   /// Key for the child container in the golden test.
   static final childKey = UniqueKey();
 
@@ -213,6 +220,7 @@ class FlutterGoldenTestAdapter extends GoldenTestAdapter {
 
   @override
   Future<void> pumpGoldenTest({
+    Key? rootKey,
     required WidgetTester tester,
     required double textScaleFactor,
     required BoxConstraints constraints,
@@ -230,6 +238,7 @@ class FlutterGoldenTestAdapter extends GoldenTestAdapter {
     await pumpWidget(
       tester,
       FlutterGoldenTestWrapper(
+        key: rootKey,
         obscureFont: obscureFont,
         globalConfigTheme: globalConfigTheme,
         variantConfigTheme: variantConfigTheme,

lib/src/golden_test_runner.dart

@@ -69,14 +69,15 @@ class FlutterGoldenTestRunner extends GoldenTestRunner {
       'Golden path must be a String or Uri.',
     );
 
-    final childKey = FlutterGoldenTestAdapter.childKey;
+    final rootKey = FlutterGoldenTestAdapter.rootKey;
 
     final mementoDebugDisableShadows = debugDisableShadows;
     debugDisableShadows = !renderShadows;
 
     try {
       await goldenTestAdapter.pumpGoldenTest(
         tester: tester,
+        rootKey: rootKey,
         textScaleFactor: textScaleFactor,
         constraints: constraints,
         obscureFont: obscureText,
@@ -92,7 +93,7 @@ class FlutterGoldenTestRunner extends GoldenTestRunner {
         cleanup = await whilePerforming(tester);
       }
 
-      final finder = find.byKey(childKey);
+      final finder = find.byKey(rootKey);
 
       final toMatch = obscureText
           ? goldenTestAdapter.getBlockedTextImage(

test/smoke_tests/dropdown_smoke_test.dart

@@ -0,0 +1,50 @@
+import 'package:alchemist/src/golden_test.dart';
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+class TestDropdownButton extends StatelessWidget {
+  const TestDropdownButton({Key? key}) : super(key: key);
+
+  @override
+  Widget build(BuildContext context) => Center(
+        child: DropdownButton<String>(
+          value: '0',
+          items: const [
+            DropdownMenuItem<String>(
+              value: '0',
+              child: Text('0'),
+            ),
+            DropdownMenuItem<String>(
+              value: '1',
+              child: Text('1'),
+            ),
+            DropdownMenuItem<String>(
+              value: '2',
+              child: Text('2'),
+            ),
+          ],
+          onChanged: (_) {},
+        ),
+      );
+}
+
+void main() {
+  group('smoke test', () {
+    goldenTest(
+      'succeeds after tapping dropdown',
+      fileName: 'dropdown_smoke_test',
+      constraints: const BoxConstraints(
+        maxWidth: 200,
+        maxHeight: 250,
+      ),
+      pumpBeforeTest: (tester) async {
+        await tester.pumpAndSettle();
+        await tester.tap(find.byType(DropdownButton<String>));
+        await tester.pumpAndSettle();
+      },
+      builder: () {
+        return const TestDropdownButton();
+      },
+    );
+  });
+}

test/src/golden_test_runner_test.dart

@@ -51,6 +51,7 @@ void main() {
 
       when(
         () => goldenTestAdapter.pumpGoldenTest(
+          rootKey: any(named: 'rootKey'),
           tester: any(named: 'tester'),
           textScaleFactor: any(named: 'textScaleFactor'),
           constraints: any(named: 'constraints'),
@@ -155,6 +156,7 @@ void main() {
       final originalSize = tester.binding.window.physicalSize;
       when(
         () => goldenTestAdapter.pumpGoldenTest(
+          rootKey: any(named: 'rootKey'),
           tester: any(named: 'tester'),
           textScaleFactor: any(named: 'textScaleFactor'),
           constraints: any(named: 'constraints'),

test/src/golden_test_test.dart

@@ -34,6 +34,7 @@ class FakeGoldenTestAdapter extends Mock implements GoldenTestAdapter {
 
   @override
   Future<void> pumpGoldenTest({
+    Key? rootKey,
     required WidgetTester tester,
     required double textScaleFactor,
     required BoxConstraints constraints,