RFR: JDK-8296240: Augment discussion of test tiers in doc/testing.md [v2]

[Daniel Fuchs]

On Thu, 26 Oct 2023 19:38:55 GMT, Joe Darcy <darcy at openjdk.org> wrote:

>> Clarify the intention of tier 1 tests. I'll reflow the paragraph and regenerate the HTML file once the wording is agreed upon.
>
> Joe Darcy has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Implement review feedback.

doc/testing.md line 141:

> 139:   Roughly speaking, a failure of a test in this tier has the potential to
> 140:   indicate a problem that would affect many Java programs. Tests in `tier1` include
> 141:   tests of HotSpot, libraries in the `java.base` module, and the `javac` compiler.

Not all libraries in `java.base` are tested in tier1. For instance, `java.net` or `java.nio` are part of tier2.
My worry here is that developers may misinterpret this statement and think the code they have modified in `java.base` will be tested if they run `tier1`. Maybe this sentence could be slightly altered to say that:

> ... `tier1` include tests of HotSpot, **some** libraries in the `java.base` module, ...

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PR Review Comment: https://git.openjdk.org/jdk/pull/16384#discussion_r1374353123