RFR: Initial section on testing

[Igor Ignatyev]

On Fri, 16 Oct 2020 16:10:13 GMT, Phil Race <prr at openjdk.org> wrote:

>> It's a start.
>
> src/index.md line 339:
> 
>> 337:
>> 338: In addition to your own Java applications, OpenJDK have support for two test frameworks, JTReg and GTest. JTReg is
>> a Java regression test framework that is used for most of the tests that are included in the OpenJDK source repository.
>> The Google Test (GTest) framework is intended for unit testing of the C++ native code. 339:
> 
> There's lots of C++ code in the JDK client - some of it shared, some of it windows specific. None of that is set up or
> likely appropriate for gtest to test it so if you are thinking of hotspot C++ code may be you should say that ..

Although I'd love to see gtest used not only for hotspot tests, it's not currently the case, so I agree with @prrace ,
you need to explicitly say that gtest is currently used/supported only for hotspot tests, all other OpenJDK test suites
are Jtreg based.

> src/index.md line 378:
> 
>> 376:
>> 377: The [JTReg documentation](https://openjdk.java.net/jtreg/) provides information on many more tags like these.
>> 378:
> 
> Also jtreg supports the @key tag which may have a value used to filter test selection. As a specific example if you
> have a UI test which needs to display a window, you should specify @key headful
> This one is important to make sure the test harness does not try to run tests on a system which does not support those
> tests.  Make sure you understand the conventions for the particular area you are testing since this is just an example.

there are other informative/useful `@key` which might make sense to mention here: `intermittent`, `randomness`, but as
Phil said, it's important to understand that different test suites/areas adop different conventions and not all
keywords are available in all test suites.

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PR: https://git.openjdk.java.net/guide/pull/30