RFR: 8346581: JRadioButton/ButtonGroupFocusTest.java fails in CI on Linux

[Harshitha Onkar]

On Wed, 8 Jan 2025 19:40:29 GMT, Alexey Ivanov <aivanov at openjdk.org> wrote:

> **Problem:**
> 
> The `javax/swing/JRadioButton/ButtonGroupFocus/ButtonGroupFocusTest.java` test fails in CI on Linux.
> 
> The focus is on _Button 2_ instead of _Button 4_.
> 
> **Root cause:**
> 
> The additional logging revealed, an expected `KEY_PRESS` event. The test uses `Robot` API to press the <kbd>Tab</kbd> key and release it. When the test fails, there are two `KEY_PRESS` events followed by a single `KEY_RELEASE` event. Because the <kbd>Tab</kbd> key is pressed twice, the focus moves twice: from _Button 2_ (the initial state) to _Button 4_ and then back to _Button 2_.
> 
> **Fix:**
> 
> Use `CountDownLatch`es to track whether a radio button received focus. Detect the case where two `KEY_PRESS` events moved focus to _Button 2_ and report the failure.
> 
> Log focus movements and dispatched key events to facilitate failure analysis.
> 
> Take a screenshot of the test frame in case of failure.
> 
> These CI hosts seem to be quite slow, removing the delay added by `robot.setAutoDelay(100)` has reduced the number of unexpected `KEY_PRESS` events. This didn't affect Windows or macOS.

CountDownLatch and additional logging LGTM. Latches might help stabilize the test on slower nodes.

test/jdk/javax/swing/JRadioButton/ButtonGroupFocus/ButtonGroupFocusTest.java line 70:

> 68:     private static final CountDownLatch button4FocusLatch = new CountDownLatch(1);
> 69: 
> 70:     private static final CountDownLatch button2FocusLatch2 = new CountDownLatch(2);

Minor: Should the no. of  button2FocusLatch2 latches be 1? since we already have another button2FocusLatch 

Suggestion:

    private static final CountDownLatch button2FocusLatch2 = new CountDownLatch(1);

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

Marked as reviewed by honkar (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/22977#pullrequestreview-2538495203
PR Review Comment: https://git.openjdk.org/jdk/pull/22977#discussion_r1907994326