tst_grabImage: Some work on looking into flakiness

* Compare old and new image sizes (to make it obvious if size is the
  part that breaks)
* Make use of the new save() functionality to dump images when it fails

Task-number: QTBUG-53793
Change-Id: I772fe4078b5a2f87aa33ceab35103ff07ee19ab2
Reviewed-by: Gunnar Sletta <gunnar@crimson.no>

1 files changed, 8 insertions, 1 deletions

diff --git a/tests/auto/qmltest/selftests/tst_grabImage.qml b/tests/auto/qmltest/selftests/tst_grabImage.qml
index 50c441ab87..7ce7e93a07 100644
--- a/tests/auto/qmltest/selftests/tst_grabImage.qml
+++ b/tests/auto/qmltest/selftests/tst_grabImage.qml
@@ -46,7 +46,14 @@ TestCase {
         oldImage = grabImage(rect);
         // Don't change anything...
         newImage = grabImage(rect);
-        verify(newImage.equals(oldImage));
+        try {
+            compare(newImage.size, oldImage.size);
+            verify(newImage.equals(oldImage));
+        } catch (ex) {
+            oldImage.save("tst_grabImage_test_equals_oldImage.png")
+            newImage.save("tst_grabImage_test_equals_newImage.png")
+            throw ex;
+        }
 
         verify(!newImage.equals(null));
         verify(!newImage.equals(undefined));