While testing JavaFX using gradle 6.3-nightly and JDK 14, I ran into what
turned out to be a latent test bug in the AppJSCallback* apps that are launched
by ModuleLauncherTest. The launched apps construct a WebView instance, obtain a
WebEngine instance from the WebView, add a state listener to the WebEngine,
load the web content, and then return from the Application::start method. The
WebView instance is held a local variable, and so is subject to garbage
collection once it goes out of scope when the start method returns.
In addition, the test apps did not check for successful launching of the
application or successful loading of the web content, which led to the test
suite hanging (else it would have been a simple test failure).
Note that I don't know (nor care) what changed in JDK 14 to make this more
likely to occur, but since the test itself is demonstrably wrong, it needs to
be fixed.
The main part of the fix was to make the WebEngine an instance variable. In
order to make the test more robust, I also modified it to launch the
application in another thread, and having the main thread check that the
application launched successfully and that the web content was loaded
successfully, after which I did the assertion check for the correct number of
callbacks.
The 5 different apps only differ from each other in the name of the class, the
name of the package from which MyCallback is imported, and possibly the
expected number of callbacks. I diffed AppJSCallbackExported.java against the
other 4 test files and the diffs are essentially the same as they were before
this change. Reviewers thus only need to review one of the tests in detail.
For example, here are the diffs between AppJSCallbackExported and
AppJSCallbackUnexported:
$ diff .../AppJSCallbackExported.java .../AppJSCallbackUnexported.java
37c37
< import myapp5.pkg2.MyCallback;
---
> import myapp5.pkg1.MyCallback;
45c45
< public class AppJSCallbackExported extends Application {
---
> public class AppJSCallbackUnexported extends Application {
77c77
< Util.assertEquals(1, callbackCount);
---
> Util.assertEquals(0, callbackCount);
-------------
Commits:
- c70d3995: 8240466: AppJSCallback* apps launched by ModuleLauncherTest
intermittently hang
Changes: https://git.openjdk.java.net/jfx/pull/134/files
Webrev: https://webrevs.openjdk.java.net/jfx/134/webrev.00
Issue: https://bugs.openjdk.java.net/browse/JDK-8240466
Stats: 265 lines in 5 files changed: 205 ins; 5 del; 55 mod
Patch: https://git.openjdk.java.net/jfx/pull/134.diff
Fetch: git fetch https://git.openjdk.java.net/jfx pull/134/head:pull/134
PR: https://git.openjdk.java.net/jfx/pull/134
