fix(model): bump version if necessary after successful bulkSave()

[vkarpov15]

Fix #15800

Summary

Make bulkSave() increment the document's version on successful save.

Need to backport this to 7.x.

Examples

[Copilot]

Pull request overview

This PR fixes issue #15800 by ensuring that bulkSave() increments the document's version key (__v) after a successful save, bringing it in line with the behavior of the regular save() method.

Key changes:

• Refactored version increment logic into a reusable _applyVersionIncrement() helper method in Document
• Modified bulkSave() to call this helper after successful writes
• Added comprehensive test coverage for version increment behavior in bulkSave()

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
lib/document.js	Adds new _applyVersionIncrement() helper method to centralize version increment logic
lib/model.js	Refactors $__save() to use the new helper and updates handleSuccessfulWrite() (used by bulkSave()) to increment versions on successful saves
test/model.test.js	Adds comprehensive test covering version increment on successful save, no increment on validation errors, and correct behavior with different field types

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[hasezoey]

Looks OK to me, but i agree with both of copilots comments / suggestions (function naming & comment location).

Just for clarification, the added test is not meant to increment version above 1?

[vkarpov15]

"Just for clarification, the added test is not meant to increment version above 1?" <-- No, because Mongoose only increments version on array updates. Updating a string property doesn't trigger a version update by default.