Improve performance of Widget Tests (#70730)

packages/flutter/lib/src/rendering/box.dart

@@ -1341,6 +1341,10 @@ class _IntrinsicDimensionsCacheEntry {
 /// [computeMinIntrinsicWidth], [computeMaxIntrinsicWidth],
 /// [computeMinIntrinsicHeight], [computeMaxIntrinsicHeight].
 ///
+/// Be sure to set [debugCheckIntrinsicSizes] to true in your unit tests if you
+/// do override any of these methods, which will add additional checks to
+/// help validate your implementation.
+///
 /// In addition, if the box has any children, it must implement
 /// [computeDistanceToActualBaseline]. [RenderProxyBox] provides a simple
 /// implementation that forwards to the child; [RenderShiftedBox] provides an
@@ -1445,6 +1449,10 @@ abstract class RenderBox extends RenderObject {
   ///
   /// This function should never return a negative or infinite value.
   ///
+  /// Be sure to set [debugCheckIntrinsicSizes] to true in your unit tests if
+  /// you do override this method, which will add additional checks to help
+  /// validate your implementation.
+  ///
   /// ## Examples
   ///
   /// ### Text
@@ -1597,6 +1605,10 @@ abstract class RenderBox extends RenderObject {
   ///
   /// This function should never return a negative or infinite value.
   ///
+  /// Be sure to set [debugCheckIntrinsicSizes] to true in your unit tests if
+  /// you do override this method, which will add additional checks to help
+  /// validate your implementation.
+  ///
   /// See also:
   ///
   ///  * [computeMinIntrinsicWidth], which has usage examples.
@@ -1675,6 +1687,10 @@ abstract class RenderBox extends RenderObject {
   ///
   /// This function should never return a negative or infinite value.
   ///
+  /// Be sure to set [debugCheckIntrinsicSizes] to true in your unit tests if
+  /// you do override this method, which will add additional checks to help
+  /// validate your implementation.
+  ///
   /// See also:
   ///
   ///  * [computeMinIntrinsicWidth], which has usage examples.
@@ -1760,6 +1776,10 @@ abstract class RenderBox extends RenderObject {
   ///
   /// This function should never return a negative or infinite value.
   ///
+  /// Be sure to set [debugCheckIntrinsicSizes] to true in your unit tests if
+  /// you do override this method, which will add additional checks to help
+  /// validate your implementation.
+  ///
   /// See also:
   ///
   ///  * [computeMinIntrinsicWidth], which has usage examples.

packages/flutter/lib/src/rendering/debug.dart

@@ -132,8 +132,9 @@ bool debugPrintLayouts = false;
 
 /// Check the intrinsic sizes of each [RenderBox] during layout.
 ///
-/// By default this is turned off since these checks are expensive, but it is
-/// enabled by the test framework.
+/// By default this is turned off since these checks are expensive. If you are
+/// implementing your own children of [RenderBox] with custom intrinsics, turn
+/// this on in your unit tests for additional validations.
 bool debugCheckIntrinsicSizes = false;
 
 /// Adds [dart:developer.Timeline] events for every [RenderObject] layout.

packages/flutter/test/flutter_test_config.dart

@@ -2,5 +2,17 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-export '_goldens_io.dart'
-  if (dart.library.html) '_goldens_web.dart' show testExecutable;
+import 'dart:async';
+
+import 'package:flutter/rendering.dart';
+
+import '_goldens_io.dart'
+  if (dart.library.html) '_goldens_web.dart' as flutter_goldens;
+
+Future<void> testExecutable(FutureOr<void> testMain()) {
+  // Enable checks because there are many implementations of [RenderBox] in this
+  // package can benefit from the additional validations.
+  debugCheckIntrinsicSizes = true;
+
+  return flutter_goldens.testExecutable(testMain);
+}

packages/flutter/test/rendering/dynamic_intrinsics_test.dart

@@ -60,6 +60,21 @@ class RenderIntrinsicSize extends RenderProxyBox {
   }
 }
 
+class RenderInvalidIntrinsics extends RenderBox {
+  @override
+  bool get sizedByParent => true;
+  @override
+  double computeMinIntrinsicWidth(double height) => -1;
+  @override
+  double computeMaxIntrinsicWidth(double height) => -1;
+  @override
+  double computeMinIntrinsicHeight(double width) => -1;
+  @override
+  double computeMaxIntrinsicHeight(double width) => -1;
+  @override
+  Size computeDryLayout(BoxConstraints constraints) => const Size(0, 0);
+}
+
 void main() {
   test('Whether using intrinsics means you get hooked into layout', () {
     RenderBox root;
@@ -84,10 +99,7 @@ void main() {
     expect(root.size, equals(inner.size));
   });
 
-  test('When RenderObject.debugCheckingIntrinsics is true, parent returns correct intrinsics', () {
-    RenderObject.debugCheckingIntrinsics = true;
-
-    try {
+  test('Parent returns correct intrinsics', () {
     RenderParentSize parent;
     RenderFixedSize inner;
 
@@ -111,9 +123,25 @@ void main() {
     pumpFrame();
 
     _expectIntrinsicDimensions(parent, 200);
-    } finally {
-      RenderObject.debugCheckingIntrinsics = false;
-    }
+  });
+
+  test('Intrinsic checks are turned on', () async {
+    final List<FlutterErrorDetails> errorDetails = <FlutterErrorDetails>[];
+    layout(RenderInvalidIntrinsics(),
+        constraints: const BoxConstraints(
+          minWidth: 0.0,
+          minHeight: 0.0,
+          maxWidth: 1000.0,
+          maxHeight: 1000.0,
+        ), onErrors: () {
+        errorDetails.addAll(renderer.takeAllFlutterErrorDetails());
+    });
+
+    expect(errorDetails, isNotEmpty);
+    expect(
+      errorDetails.map((FlutterErrorDetails details) => details.toString()),
+      everyElement(contains('violate the intrinsic protocol')),
+    );
   });
 }
 

packages/flutter_test/lib/src/binding.dart

@@ -181,7 +181,6 @@ abstract class TestWidgetsFlutterBinding extends BindingBase
   TestWidgetsFlutterBinding() : _window = TestWindow(window: ui.window) {
     debugPrint = debugPrintOverride;
     debugDisableShadows = disableShadows;
-    debugCheckIntrinsicSizes = checkIntrinsicSizes;
   }
 
   @override
@@ -287,14 +286,6 @@ abstract class TestWidgetsFlutterBinding extends BindingBase
   /// equivalent as [Future.delayed].
   Future<void> delayed(Duration duration);
 
-  /// The value to set [debugCheckIntrinsicSizes] to while tests are running.
-  ///
-  /// This can be used to enable additional checks. For example,
-  /// [AutomatedTestWidgetsFlutterBinding] sets this to true, so that all tests
-  /// always run with aggressive intrinsic sizing tests enabled.
-  @protected
-  bool get checkIntrinsicSizes => false;
-
   /// Creates and initializes the binding. This function is
   /// idempotent; calling it a second time will just return the
   /// previously-created instance.
@@ -782,6 +773,8 @@ abstract class TestWidgetsFlutterBinding extends BindingBase
 
   Future<void> _runTestBody(Future<void> testBody(), VoidCallback invariantTester) async {
     assert(inTest);
+    // So that we can assert that it remains the same after the test finishes.
+    _beforeTestCheckIntrinsicSizes = debugCheckIntrinsicSizes;
 
     runApp(Container(key: UniqueKey(), child: _preTestMessage)); // Reset the tree to a known state.
     await pump();
@@ -814,6 +807,8 @@ abstract class TestWidgetsFlutterBinding extends BindingBase
     asyncBarrier(); // When using AutomatedTestWidgetsFlutterBinding, this flushes the microtasks.
   }
 
+  late bool _beforeTestCheckIntrinsicSizes;
+
   void _verifyInvariants() {
     assert(debugAssertNoTransientCallbacks(
       'An animation is still running even after the widget tree was disposed.'
@@ -831,7 +826,7 @@ abstract class TestWidgetsFlutterBinding extends BindingBase
     ));
     assert(debugAssertAllRenderVarsUnset(
       'The value of a rendering debug variable was changed by the test.',
-      debugCheckIntrinsicSizesOverride: checkIntrinsicSizes,
+      debugCheckIntrinsicSizesOverride: _beforeTestCheckIntrinsicSizes,
     ));
     assert(debugAssertAllWidgetVarsUnset(
       'The value of a widget debug variable was changed by the test.',
@@ -944,9 +939,6 @@ class AutomatedTestWidgetsFlutterBinding extends TestWidgetsFlutterBinding {
   @override
   bool get disableShadows => true;
 
-  @override
-  bool get checkIntrinsicSizes => true;
-
   /// The value of [defaultTestTimeout] can be set to `None` to enable debugging flutter tests where
   /// we would not want to timeout the test. This is expected to be used by test tooling which
   /// can detect debug mode.