RFR: 8285295: Need better testing for IdentityHashMap

[Jaikiran Pai]

On Fri, 22 Apr 2022 03:37:27 GMT, Stuart Marks <smarks 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?

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