update buttons_test to expect clipPath instead of clipRRect

packages/flutter/test/material/buttons_test.dart

@@ -200,10 +200,19 @@ void main() {
     await tester.pump(); // start gesture
     await tester.pump(const Duration(milliseconds: 200)); // wait for splash to be well under way
 
+    final Rect expectedClipRect = new Rect.fromLTRB(356.0, 282.0, 444.0, 318.0);
+    final Path expectedClipPath = new Path()
+     ..addRRect(new RRect.fromRectAndRadius(
+         expectedClipRect,
+         const Radius.circular(2.0),
+     ));
     expect(
       Material.of(tester.element(find.byType(MaterialButton))),
       paints
-        ..clipRRect(rrect: new RRect.fromLTRBR(356.0, 282.0, 444.0, 318.0, const Radius.circular(2.0)))
+        ..clipPath(pathMatcher: coversSameAreaAs(
+            expectedClipPath,
+            areaToCompare: expectedClipRect.inflate(10.0),
+        ))
         ..circle(color: directSplashColor)
         ..rect(color: directHighlightColor)
     );
@@ -235,7 +244,10 @@ void main() {
     expect(
       Material.of(tester.element(find.byType(MaterialButton))),
       paints
-        ..clipRRect(rrect: new RRect.fromLTRBR(356.0, 282.0, 444.0, 318.0, const Radius.circular(2.0)))
+        ..clipPath(pathMatcher: coversSameAreaAs(
+            expectedClipPath,
+            areaToCompare: expectedClipRect.inflate(10.0),
+        ))
         ..circle(color: themeSplashColor1)
         ..rect(color: themeHighlightColor1)
     );

packages/flutter/test/rendering/mock_canvas.dart

@@ -148,6 +148,18 @@ abstract class PaintPattern {
   /// [Canvas.clipRect] call are ignored.
   void clipRect({ Rect rect });
 
+  /// Indicates that a path clip is expected next.
+  ///
+  /// The next path clip is examined.
+  /// The path that is passed to the actual [Canvas.clipPath] call is matched
+  /// using [pathMatcher].
+  ///
+  /// If no call to [Canvas.clipPath] was made, then this results in failure.
+  ///
+  /// Any calls made between the last matched call (if any) and the
+  /// [Canvas.clipPath] call are ignored.
+  void clipPath({Matcher pathMatcher});
+
   /// Indicates that a rectangle is expected next.
   ///
   /// The next rectangle is examined. Any arguments that are passed to this
@@ -629,6 +641,11 @@ class _TestRecordingCanvasPatternMatcher extends _TestRecordingCanvasMatcher imp
     _predicates.add(new _FunctionPaintPredicate(#clipRect, <dynamic>[rect]));
   }
 
+  @override
+  void clipPath({Matcher pathMatcher}) {
+    _predicates.add(new _FunctionPaintPredicate(#clipPath, <dynamic>[pathMatcher]));
+  }
+
   @override
   void rect({ Rect rect, Color color, double strokeWidth, bool hasMaskFilter, PaintingStyle style }) {
     _predicates.add(new _RectPaintPredicate(rect: rect, color: color, strokeWidth: strokeWidth, hasMaskFilter: hasMaskFilter, style: style));