tst_grabImage: Fix the cases were visually comparing invisible items

TestCase item has 'visible: false' set by default, and the grabImage()
gets the data from QWindow surface.

Make the root item visible so the test can get some data and actually
check something.

Also check the color of some grabbed pixels to see if we're working
with the blank window background (before the root item 'visible'
changed to 'true') or with the target item (after the fix).

Change-Id: I107799a7442a62d44786003179e4595694c651a7
Reviewed-by: Shawn Rutledge <shawn.rutledge@qt.io>
Reviewed-by: Mitch Curtis <mitch.curtis@qt.io>
(cherry picked from commit aed93ada4e58db8f1c36d7ed2c1074a514caf45a)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

1 files changed, 5 insertions, 0 deletions

diff --git a/tests/auto/qmltest/selftests/tst_grabImage.qml b/tests/auto/qmltest/selftests/tst_grabImage.qml
index 7ce7e93a07..714bc07f27 100644
--- a/tests/auto/qmltest/selftests/tst_grabImage.qml
+++ b/tests/auto/qmltest/selftests/tst_grabImage.qml
@@ -34,6 +34,7 @@ TestCase {
     id: testCase
     name: "tst_grabImage"
     when: windowShown
+    visible: true
 
     function test_equals() {
         var rect = createTemporaryQmlObject("import QtQuick 2.0; Rectangle { color: 'red'; width: 10; height: 10; }", testCase);
@@ -47,6 +48,8 @@ TestCase {
         // Don't change anything...
         newImage = grabImage(rect);
         try {
+            // Check that we actually grabbed something
+            compare(newImage.pixel(0, 0), "#ff0000")
             compare(newImage.size, oldImage.size);
             verify(newImage.equals(oldImage));
         } catch (ex) {
@@ -86,6 +89,8 @@ TestCase {
 
         try {
             verify(grabbedImage2.equals(grabbedImage))
+            // Check that we actually grabbed, saved, and loaded something
+            compare(grabbedImage2.pixel(0, 0), "#ff0000")
         } catch (ex) {
             grabbedImage2.save("tst_grabImage_test_save2.png")
             throw ex;