RFR: 8377189: Intermittent failure in TooltipTest.testCssStylesheetChangeTooltip

[Kevin Rushforth]

On Fri, 6 Feb 2026 02:33:02 GMT, Michael Strauß <mstrauss at openjdk.org> wrote:

> `test.robot.javafx.scene.TooltipTest` modifies the scene graph on a test worker thread, which can corrupt the scene graph and leads to test failures such as:
> 
> 
> TooltipTest > testCssStylesheetChangeTooltip() FAILED
>     java.lang.AssertionError
>         at [javafx.graphics at 27-ea](mailto:javafx.graphics at 27-ea)/com.sun.javafx.css.StyleMap.getCascadingStyles(StyleMap.java:144)
>         at [javafx.graphics at 27-ea](mailto:javafx.graphics at 27-ea)/javafx.scene.CssStyleHelper.resetToInitialValues(CssStyleHelper.java:490)
>         at [javafx.graphics at 27-ea](mailto:javafx.graphics at 27-ea)/javafx.scene.CssStyleHelper.createStyleHelper(CssStyleHelper.java:193)
>         at [javafx.graphics at 27-ea](mailto:javafx.graphics at 27-ea)/javafx.scene.Node.reapplyCss(Node.java:9996)
>         at [javafx.graphics at 27-ea](mailto:javafx.graphics at 27-ea)/javafx.scene.Node.reapplyCSS(Node.java:9959)
>         at [javafx.graphics at 27-ea](mailto:javafx.graphics at 27-ea)/javafx.scene.Scene$10.onChanged(Scene.java:1682)
>         at [javafx.base at 27-ea](mailto:javafx.base at 27-ea)/com.sun.javafx.collections.TrackableObservableList.lambda$new$0(TrackableObservableList.java:44)
>         at [javafx.base at 27-ea](mailto:javafx.base at 27-ea)/com.sun.javafx.collections.ListListenerHelper$SingleChange.fireValueChangedEvent(ListListenerHelper.java:162)
>         at [javafx.base at 27-ea](mailto:javafx.base at 27-ea)/com.sun.javafx.collections.ListListenerHelper.fireValueChangedEvent(ListListenerHelper.java:71)
>         at [javafx.base at 27-ea](mailto:javafx.base at 27-ea)/javafx.collections.ObservableListBase.fireChange(ObservableListBase.java:246)
>         at [javafx.base at 27-ea](mailto:javafx.base at 27-ea)/javafx.collections.ListChangeBuilder.commit(ListChangeBuilder.java:482)
>         at [javafx.base at 27-ea](mailto:javafx.base at 27-ea)/javafx.collections.ListChangeBuilder.endChange(ListChangeBuilder.java:541)
> 
> 
> or
> 
> 
> TooltipTest > testCssStylesheetChangeTooltip() STANDARD_ERROR
>     Exception in thread "JavaFX Application Thread" java.lang.NullPointerException: Cannot invoke "java.util.List.clear()" because "this.selectors" is null
>         at [javafx.graphics at 27-internal](mailto:javafx.graphics at 27-internal)/com.sun.javafx.css.StyleMap.getCascadingStyles(StyleMap.java:148)
>         at [javafx.graphics at 27-internal](mailto:javafx.graphics at 27-internal)/javafx.scene.CssStyleHelper.resetToInitialValues(CssStyleHelper.java:490)
>         at [javafx.graphics at 27-internal](mailto:javafx.graphics at 27-internal)/javafx.scene.CssStyleHelper.createStyleHelper(CssSt...

@mstr2 Both Lukazs and Andy have made the case for also changing the DELTA value as part of this fix to eliminate another source of intermittent failures in this test. The PR is already approved, so it's up to you. If you do want to update it, maybe increasing the delta from 100 to either 150 or 200 might be reasonable. Otherwise, we'll file a follow-on bug so we'll have something tracking it in case we ever see it in the wild.

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PR Comment: https://git.openjdk.org/jfx/pull/2066#issuecomment-3861976950