Atomic set+delete on Map produces incorrect patches

[jscheid]

🐛 Bug Report

Hi, big fan of immer here! I think I've found a small issue though:

When adding an element to an object ({}) and then immediately removing it (via applyPatches), produceWithPatches returns an empty patch set as expected, since ultimately nothing has changed.

When doing the same with a Map however, the reported resulting patch set contains only a patch for removing the element. Replaying that patch set (or replaying the reverse patch set on top of the produced result) would produce inconsistent results.

Link to repro

https://codesandbox.io/s/immer-addthenremovepatches-for-map-d4jve?file=/tests/immer.test.ts

To Reproduce

Steps to reproduce the behavior: see repro.

Observed behavior

The resulting patches are different depending on whether the changes were applied to an object or a Map.

Expected behavior

I'd expect the patches to be the same in both cases. At least, I'd expect the patches resulting for Map to be consistent -- for example, an add patch followed by a remove patch.

Environment

We only accept bug reports against the latest Immer version.

• Immer version:
• I filed this report against the latest version of Immer
• Occurs with setUseProxies(true)
• Occurs with setUseProxies(false) (ES5 only)