Fix clip debugPaint (TextPainter RTL fallout) (#12026)

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

@@ -1039,6 +1039,7 @@ abstract class _RenderCustomClip<T> extends RenderProxyBox {
               fontSize: 14.0,
             ),
           ),
+          textDirection: TextDirection.rtl, // doesn't matter, it's one character
         )
         ..layout();
       return true;

packages/flutter/test/rendering/mock_canvas.dart

@@ -260,6 +260,10 @@ abstract class _TestRecordingCanvasMatcher extends Matcher {
   bool matches(Object object, Map<dynamic, dynamic> matchState) {
     final TestRecordingCanvas canvas = new TestRecordingCanvas();
     final TestRecordingPaintingContext context = new TestRecordingPaintingContext(canvas);
+    final StringBuffer description = new StringBuffer();
+    String prefixMessage = 'unexpectedly failed.';
+    bool result = false;
+    try {
       if (object is _ContextPainterFunction) {
         final _ContextPainterFunction function = object;
         function(context, Offset.zero);
@@ -280,14 +284,22 @@ abstract class _TestRecordingCanvasMatcher extends Matcher {
           return false;
         }
       }
-    final StringBuffer description = new StringBuffer();
-    final bool result = _evaluatePredicates(canvas.invocations, description);
+      result = _evaluatePredicates(canvas.invocations, description);
+      if (!result)
+        prefixMessage = 'did not match the pattern.';
+    } catch (error, stack) {
+      prefixMessage = 'threw the following exception:';
+      description.writeln(error.toString());
+      description.write(stack.toString());
+      result = false;
+    }
     if (!result) {
-      if (canvas.invocations.isNotEmpty)
+      if (canvas.invocations.isNotEmpty) {
         description.write('The complete display list was:');
         for (RecordedInvocation call in canvas.invocations)
           description.write('\n  * $call');
-      matchState[this] = 'did not match the pattern.\n$description';
+      }
+      matchState[this] = '$prefixMessage\n$description';
     }
     return result;
   }

packages/flutter/test/widgets/clip_test.dart

@@ -4,6 +4,9 @@
 
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter/material.dart';
+import 'package:flutter/rendering.dart';
+
+import '../rendering/mock_canvas.dart';
 
 final List<String> log = <String>[];
 
@@ -223,4 +226,25 @@ void main() {
     expect(log, equals(<String>['a', 'tap', 'a', 'b', 'c', 'tap']));
   });
 
+  testWidgets('debugPaintSizeEnabled', (WidgetTester tester) async {
+    await tester.pumpWidget(
+      const ClipRect(
+        child: const Placeholder(),
+      ),
+    );
+    expect(tester.renderObject(find.byType(ClipRect)).paint, paints
+      ..save()
+      ..clipRect(rect: new Rect.fromLTRB(0.0, 0.0, 800.0, 600.0))
+      ..save()
+      ..path() // Placeholder
+      ..restore()
+      ..restore()
+    );
+    debugPaintSizeEnabled = true;
+    expect(tester.renderObject(find.byType(ClipRect)).debugPaint, paints // ignore: INVALID_USE_OF_PROTECTED_MEMBER
+      ..rect(rect: new Rect.fromLTRB(0.0, 0.0, 800.0, 600.0))
+      ..paragraph()
+    );
+    debugPaintSizeEnabled = false;
+  });
 }