RFR: 8305608: Change VMConnection to use "test.class.path"instead of "test.classes"

[Leonid Mesnik]

On Tue, 4 Apr 2023 23:08:06 GMT, Serguei Spitsyn <sspitsyn at openjdk.org> wrote:

>> Currently, VMConnection run debugee using "test.classes" as a classpath. It cause test failures when virtual thread factory (wrapper) is enabled and test is not located the same directory as TestScaffold.
>
> test/jdk/com/sun/jdi/VMConnection.java line 54:
> 
>> 52:         // When we run under jtreg, test.classes contains the pathname of
>> 53:         // the dir in which the .class files will be placed.
>> 54:         // When we run jtreg with plugin, the TestScaffold should be also in classpath
> 
> A stupid question about this part of comment: `the TestScaffold should be also in classpath`.
> If it should be ALSO in classpath then why in the `Virtual` case we use "test.class.path" instead of "test.classes" but not both. It'd be good to clarify this in the comment.

The "test.class.path" is complete classpath required to run test. It included test.classes as well as testlibrary and some other classes. The tests located in com/sun/jdi/<subdirectory> uses 'com/sun/jdi' as a testlibrary.
The better comment would be
// When we run jtreg with plugin, the full classpath including testlibrary is required to use TestScaffold is required

However, before fixing this comment I would like to see if there are any objections against using "test.class.path"  in all cases. It would minimize difference in virtual and standard mode. 
Is there are any reason to use "test.classes" at all?

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PR Review Comment: https://git.openjdk.org/jdk/pull/13339#discussion_r1157871028