RFR: 8285295: Need better testing for IdentityHashMap

[Stuart Marks]

On Thu, 28 Apr 2022 13:22:34 GMT, Jaikiran Pai <jpai at openjdk.org> wrote:

>> Basic but fairly comprehensive set of tests for `IdentityHashMap`. The patch in the bug report that breaks `IdentityHashMap` now causes several cases in this new test to fail. There's more that could be done, but the new tests cover most of the core functions of `IdentityHashMap`. Unfortunately it seems difficult to merge this with the existing, comprehensive Collections tests (e.g., MOAT.java) because those tests implicity rely on `equals()`-based contract instead of the special-purpose `==`-based contract used by `IdentityHashMap`.
>
> test/jdk/java/util/IdentityHashMap/Basic.java line 337:
> 
>> 335:     public void testPutOverwrite() {
>> 336:         Box newVal = new Box(v1a);
>> 337:         map.put(k1a, newVal);
> 
> Should we capture the return value and assert that it's not null and is identity equal to `v1a`?
> 
> Perhaps, similarly at a few other places where we do put and putIfAbsent?

Yes, good point, I'll add checks of the return values in the appropriate places. There are several, including `remove`, `computeX`, `put`, etc.

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PR: https://git.openjdk.java.net/jdk/pull/8354