Error message when size has not been set in RenderBox's performLayout should...

Error message when size has not been set in RenderBox's performLayout should be well versed (#58151)

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

@@ -1927,7 +1927,6 @@ abstract class RenderBox extends RenderObject {
     assert(constraints != null);
     assert(() {
       if (!hasSize) {
-        assert(!debugNeedsLayout); // this is called in the size= setter during layout, but in that case we have a size
         DiagnosticsNode contract;
         if (sizedByParent)
           contract = ErrorDescription('Because this RenderBox has sizedByParent set to true, it must set its size in performResize().');

packages/flutter/test/rendering/box_test.dart

@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import 'package:flutter/foundation.dart';
 import 'package:flutter/gestures.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter/rendering.dart';
@@ -30,6 +31,11 @@ class FakeMissingSizeRenderBox extends RenderBox {
   bool fakeMissingSize = false;
 }
 
+class MissingSetSizeRenderBox extends RenderBox {
+  @override
+  void performLayout() { }
+}
+
 void main() {
   test('should size to render view', () {
     final RenderBox root = RenderDecoratedBox(
@@ -1014,6 +1020,34 @@ void main() {
     expect(() => BoxConstraints(minHeight: null), throwsAssertionError);
     expect(() => BoxConstraints(maxHeight: null), throwsAssertionError);
   });
+
+  test('Error message when size has not been set in RenderBox performLayout should be well versed', () {
+    FlutterErrorDetails errorDetails;
+    final FlutterExceptionHandler oldHandler = FlutterError.onError;
+    FlutterError.onError = (FlutterErrorDetails details) {
+      errorDetails = details;
+    };
+    try {
+      MissingSetSizeRenderBox().layout(const BoxConstraints());
+    } finally {
+      FlutterError.onError = oldHandler;
+    }
+
+    expect(errorDetails, isNotNull);
+
+    // Check the ErrorDetails without the stack trace.
+    final List<String> lines =  errorDetails.toString().split('\n');
+    expect(
+      lines.take(5).join('\n'),
+      equalsIgnoringHashCodes(
+        '══╡ EXCEPTION CAUGHT BY RENDERING LIBRARY ╞══════════════════════\n'
+          'The following assertion was thrown during performLayout():\n'
+          'RenderBox did not set its size during layout.\n'
+          'Because this RenderBox has sizedByParent set to false, it must\n'
+          'set its size in performLayout().'
+      ),
+    );
+  });
 }
 
 class _DummyHitTestTarget implements HitTestTarget {