From acf1fb644f4d23a878c9c38e79d19de3cd999890 Mon Sep 17 00:00:00 2001
From: Kate Lovett <katelovett@google.com>
Date: Mon, 24 Jun 2024 11:00:53 -0700
Subject: [PATCH] Fix flaky sliver tree test (#150707)

The set of nodes being used in the tree test was not being consistently
reset at the beginning of every test. The tree is currently broken
because today's random seed for test ordering exposed this leak of state
from one test to another.

Fixes https://github.com/flutter/flutter/issues/150706

## Pre-launch Checklist

- [x] I read the [Contributor Guide] and followed the process outlined
there for submitting PRs.
- [x] I read the [Tree Hygiene] wiki page, which explains my
responsibilities.
- [x] I read and followed the [Flutter Style Guide], including [Features
we expect every widget to implement].
- [x] I signed the [CLA].
- [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].
- [x] I followed the [breaking change policy] and added [Data Driven
Fixes] where supported.
- [x] All existing and new tests are passing.

If you need help, consider asking for advice on the #hackers-new channel
on [Discord].

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https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#overview
[Tree Hygiene]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md
[test-exempt]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#tests
[Flutter Style Guide]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md
[Features we expect every widget to implement]:
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[flutter/tests]: https://github.com/flutter/tests
[breaking change policy]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#handling-breaking-changes
[Discord]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Chat.md
[Data Driven Fixes]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Data-driven-Fixes.md
---
 .../test/widgets/sliver_tree_test.dart        | 64 +++++++++++++++++++
 1 file changed, 64 insertions(+)

diff --git a/packages/flutter/test/widgets/sliver_tree_test.dart b/packages/flutter/test/widgets/sliver_tree_test.dart
index a10277c7961f..a7a7a2581ecd 100644
--- a/packages/flutter/test/widgets/sliver_tree_test.dart
+++ b/packages/flutter/test/widgets/sliver_tree_test.dart
@@ -28,6 +28,29 @@ List<TreeSliverNode<String>> simpleNodeSet = <TreeSliverNode<String>>[
 
 void main() {
   group('TreeSliverNode', () {
+    setUp(() {
+      // Reset node conditions for each test.
+      simpleNodeSet = <TreeSliverNode<String>>[
+        TreeSliverNode<String>('Root 0'),
+        TreeSliverNode<String>(
+          'Root 1',
+          expanded: true,
+          children: <TreeSliverNode<String>>[
+            TreeSliverNode<String>('Child 1:0'),
+            TreeSliverNode<String>('Child 1:1'),
+          ],
+        ),
+        TreeSliverNode<String>(
+          'Root 2',
+          children: <TreeSliverNode<String>>[
+            TreeSliverNode<String>('Child 2:0'),
+            TreeSliverNode<String>('Child 2:1'),
+          ],
+        ),
+        TreeSliverNode<String>('Root 3'),
+      ];
+    });
+
     test('getters, toString', () {
       final List<TreeSliverNode<String>> children = <TreeSliverNode<String>>[
         TreeSliverNode<String>('child'),
@@ -123,6 +146,7 @@ void main() {
         TreeSliverNode<String>('Root 3'),
       ];
     });
+
     testWidgets('Can set controller on TreeSliver', (WidgetTester tester) async {
       final TreeSliverController controller = TreeSliverController();
       TreeSliverController? returnedController;
@@ -427,6 +451,26 @@ void main() {
   });
 
   testWidgets('.toggleNodeWith, onNodeToggle', (WidgetTester tester) async {
+    simpleNodeSet = <TreeSliverNode<String>>[
+      TreeSliverNode<String>('Root 0'),
+      TreeSliverNode<String>(
+        'Root 1',
+        expanded: true,
+        children: <TreeSliverNode<String>>[
+          TreeSliverNode<String>('Child 1:0'),
+          TreeSliverNode<String>('Child 1:1'),
+        ],
+      ),
+      TreeSliverNode<String>(
+        'Root 2',
+        children: <TreeSliverNode<String>>[
+          TreeSliverNode<String>('Child 2:0'),
+          TreeSliverNode<String>('Child 2:1'),
+        ],
+      ),
+      TreeSliverNode<String>('Root 3'),
+    ];
+
     final TreeSliverController controller = TreeSliverController();
     // The default node builder wraps the leading icon with toggleNodeWith.
     bool toggled = false;
@@ -516,6 +560,26 @@ void main() {
   });
 
   testWidgets('AnimationStyle is piped through to node builder', (WidgetTester tester) async {
+    simpleNodeSet = <TreeSliverNode<String>>[
+      TreeSliverNode<String>('Root 0'),
+      TreeSliverNode<String>(
+        'Root 1',
+        expanded: true,
+        children: <TreeSliverNode<String>>[
+          TreeSliverNode<String>('Child 1:0'),
+          TreeSliverNode<String>('Child 1:1'),
+        ],
+      ),
+      TreeSliverNode<String>(
+        'Root 2',
+        children: <TreeSliverNode<String>>[
+          TreeSliverNode<String>('Child 2:0'),
+          TreeSliverNode<String>('Child 2:1'),
+        ],
+      ),
+      TreeSliverNode<String>('Root 3'),
+    ];
+
     AnimationStyle? style;
     await tester.pumpWidget(MaterialApp(
       home: CustomScrollView(