RFR: 8359598: [TestBug] VirtualFlowTestUtils should not create a temporary Stage

[Andy Goryachev]

On Sun, 15 Jun 2025 13:56:05 GMT, Marius Hanl <mhanl at openjdk.org> wrote:

> Currently, the VirtualFlowTestUtils used ONLY for tests has many utility methods to get and do something with the VirtualFlow of Virtualized Controls.
> 
> It has one flaw: It may creates a temporary Stage with the StageLoader, when the Control was never inside a Scene (and Stage) yet. This is done to get the VirtualFlow, which is not possible otherwise.
> 
> Take the following test code:
> 
> VirtualFlowTestUtils.clickOnRow(tableView, 2);
> VirtualFlowTestUtils.clickOnRow(tableView, 4);
> 
> 
> What it does it to create a Stage for the first method and dispose it after. And create another Stage for the second method and dispose it after.
> 
> This does not test a realistic scenario and the chance is quite high that developers used that methods without even knowing that it contains such logic.
> 
> So the idea is to remove the StageLoader code from VirtualFlowTestUtils and rather use it in the Test code before calling the Util methods.
> 
> For the example above, this would result in:
> 
> stageLoader = new StageLoader(tableView);
> VirtualFlowTestUtils.clickOnRow(tableView, 2);
> VirtualFlowTestUtils.clickOnRow(tableView, 4);
> 
> 
> The stageLoader should be disposed in an @AfterEach.
> 
> Note: Nearly all touched tests are indeed much older test code. New tests are not affected and already use it correcty.
> Sometimes a call to `Toolkit.getToolkit().firePulse();` was needed. Previously, creating a new Stage for every call to the util methods did that implicitly.

It's a trivial change, but I wonder if 2 reviewers are needed.

modules/javafx.controls/src/test/java/test/com/sun/javafx/scene/control/infrastructure/VirtualFlowTestUtils.java line 349:

> 347:         flow = (VirtualFlow<?>)control.lookup("#virtual-flow");
> 348: 
> 349:         if (sl != null) {

should we have a check here with a helpful message (which recommends to use `StageLoader`), instead of returning `null`?

-------------

PR Review: https://git.openjdk.org/jfx/pull/1829#pullrequestreview-2932969739
PR Review Comment: https://git.openjdk.org/jfx/pull/1829#discussion_r2150529464