1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
// Copyright 2014 The Flutter 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/widgets.dart';
import 'package:flutter_test/flutter_test.dart';
import 'package:leak_tracker_flutter_testing/leak_tracker_flutter_testing.dart';
import 'test_widgets.dart';
class ProbeWidget extends StatefulWidget {
const ProbeWidget({ super.key });
@override
ProbeWidgetState createState() => ProbeWidgetState();
}
class ProbeWidgetState extends State<ProbeWidget> {
static int buildCount = 0;
@override
void initState() {
super.initState();
setState(() { });
}
@override
void didUpdateWidget(ProbeWidget oldWidget) {
super.didUpdateWidget(oldWidget);
setState(() { });
}
@override
Widget build(BuildContext context) {
setState(() { });
buildCount++;
return Container();
}
}
class BadWidget extends StatelessWidget {
const BadWidget(this.parentState, { super.key });
final BadWidgetParentState parentState;
@override
Widget build(BuildContext context) {
parentState._markNeedsBuild();
return Container();
}
}
class BadWidgetParent extends StatefulWidget {
const BadWidgetParent({ super.key });
@override
BadWidgetParentState createState() => BadWidgetParentState();
}
class BadWidgetParentState extends State<BadWidgetParent> {
void _markNeedsBuild() {
setState(() {
// Our state didn't really change, but we're doing something pathological
// here to trigger an interesting scenario to test.
});
}
@override
Widget build(BuildContext context) {
return BadWidget(this);
}
}
class BadDisposeWidget extends StatefulWidget {
const BadDisposeWidget({ super.key });
@override
BadDisposeWidgetState createState() => BadDisposeWidgetState();
}
class BadDisposeWidgetState extends State<BadDisposeWidget> {
@override
Widget build(BuildContext context) {
return Container();
}
@override
void dispose() {
setState(() { /* This is invalid behavior. */ });
super.dispose();
}
}
class StatefulWrapper extends StatefulWidget {
const StatefulWrapper({
super.key,
required this.child,
});
final Widget child;
@override
StatefulWrapperState createState() => StatefulWrapperState();
}
class StatefulWrapperState extends State<StatefulWrapper> {
void trigger() {
setState(() { built = null; });
}
int? built;
late int oldBuilt;
static int buildId = 0;
@override
Widget build(BuildContext context) {
buildId += 1;
built = buildId;
return widget.child;
}
}
class Wrapper extends StatelessWidget {
const Wrapper({
super.key,
required this.child,
});
final Widget child;
@override
Widget build(BuildContext context) {
return child;
}
}
void main() {
testWidgetsWithLeakTracking('Legal times for setState', (WidgetTester tester) async {
final GlobalKey flipKey = GlobalKey();
expect(ProbeWidgetState.buildCount, equals(0));
await tester.pumpWidget(const ProbeWidget(key: Key('a')));
expect(ProbeWidgetState.buildCount, equals(1));
await tester.pumpWidget(const ProbeWidget(key: Key('b')));
expect(ProbeWidgetState.buildCount, equals(2));
await tester.pumpWidget(FlipWidget(
key: flipKey,
left: Container(),
right: const ProbeWidget(key: Key('c')),
));
expect(ProbeWidgetState.buildCount, equals(2));
final FlipWidgetState flipState1 = flipKey.currentState! as FlipWidgetState;
flipState1.flip();
await tester.pump();
expect(ProbeWidgetState.buildCount, equals(3));
final FlipWidgetState flipState2 = flipKey.currentState! as FlipWidgetState;
flipState2.flip();
await tester.pump();
expect(ProbeWidgetState.buildCount, equals(3));
await tester.pumpWidget(Container());
expect(ProbeWidgetState.buildCount, equals(3));
});
testWidgets('Setting parent state during build is forbidden', (WidgetTester tester) async {
await tester.pumpWidget(const BadWidgetParent());
expect(tester.takeException(), isFlutterError);
await tester.pumpWidget(Container());
});
testWidgets('Setting state during dispose is forbidden', (WidgetTester tester) async {
await tester.pumpWidget(const BadDisposeWidget());
expect(tester.takeException(), isNull);
await tester.pumpWidget(Container());
expect(tester.takeException(), isNotNull);
});
testWidgetsWithLeakTracking('Dirty element list sort order', (WidgetTester tester) async {
final GlobalKey key1 = GlobalKey(debugLabel: 'key1');
final GlobalKey key2 = GlobalKey(debugLabel: 'key2');
bool didMiddle = false;
late Widget middle;
final List<StateSetter> setStates = <StateSetter>[];
Widget builder(BuildContext context, StateSetter setState) {
setStates.add(setState);
final bool returnMiddle = !didMiddle;
didMiddle = true;
return Wrapper(
child: Wrapper(
child: StatefulWrapper(
child: returnMiddle ? middle : Container(),
),
),
);
}
final Widget part1 = Wrapper(
child: KeyedSubtree(
key: key1,
child: StatefulBuilder(
builder: builder,
),
),
);
final Widget part2 = Wrapper(
child: KeyedSubtree(
key: key2,
child: StatefulBuilder(
builder: builder,
),
),
);
middle = part2;
await tester.pumpWidget(part1);
for (final StatefulWrapperState state in tester.stateList<StatefulWrapperState>(find.byType(StatefulWrapper))) {
expect(state.built, isNotNull);
state.oldBuilt = state.built!;
state.trigger();
}
for (final StateSetter setState in setStates) {
setState(() { });
}
StatefulWrapperState.buildId = 0;
middle = part1;
didMiddle = false;
await tester.pumpWidget(part2);
for (final StatefulWrapperState state in tester.stateList<StatefulWrapperState>(find.byType(StatefulWrapper))) {
expect(state.built, isNotNull);
expect(state.built, isNot(equals(state.oldBuilt)));
}
});
}