RFR: 8367991: Update RegionBackground tests to use ScreenCaptureTestWatcher utility [v4]

[Kevin Rushforth]

On Mon, 22 Sep 2025 10:22:47 GMT, Jayathirth D V <jdv at openjdk.org> wrote:

>> We are seeing very rare intermittent failures in RegionBackgroundFillUITest & RegionBackgroundImageUITest tests in linux. We already have [JDK-8328217](https://bugs.openjdk.org/browse/JDK-8328217) to fix this issue.
>> 
>> To identify the root cause better, we want to capture the test content when it is failing using ScreenCaptureTestWatcher utility.
>> 
>> Since we want to capture the test window before test stage is cleared. We are now clearing the test stage in the next test setup. Initially tried updating this behaviour in `VisualTestBase` itself, but that causes tests like `test.robot.test3d.PointLightIlluminationTest` to fail as it overrides the test setup functions.
>> 
>> This change is tested to make sure ScreenCaptureTestWatcher takes appropriate screen capture on failure and CI full headful test run is green.
>
> Jayathirth D V has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Add flag to disable stage clearing

LGTM. I left a couple minor comments inline and will reapprove if you make any changes.

tests/system/src/test/java/test/robot/test3d/PointLightIlluminationTest.java line 85:

> 83:             // Ensure that the scene is really displayed, before the tests begin
> 84:             waitFirstFrame();
> 85:             // The same scene can be used for all the illumination tests by this class

Minor: "scene" --> "stage" ?

tests/system/src/test/java/test/robot/testharness/VisualTestBase.java line 63:

> 61:     Robot robot;
> 62: 
> 63:     protected static boolean clearStage = true;

Minor: would `clearStages` (plural) be a better name?

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Marked as reviewed by kcr (Lead).

PR Review: https://git.openjdk.org/jfx/pull/1913#pullrequestreview-3253080942
PR Review Comment: https://git.openjdk.org/jfx/pull/1913#discussion_r2368637235
PR Review Comment: https://git.openjdk.org/jfx/pull/1913#discussion_r2368640274