Recalculate mentions of forwarded messages

[twassman]

In transformEvent(), parse event body back into an EditorModel, and pass this into attachMentions(), so that it actually recalculates mentions based on the message body.

Follow up to #30884.

Checklist

• [x] I have read through review guidelines and CONTRIBUTING.md.
• [ ] Tests written for new code (and old code if feasible).
• [x] New or updated public/exported symbols have accurate TSDoc documentation.
• [x] Linter and other CI checks pass.
• [x] I have licensed the changes to Element by completing the Contributor License Agreement (CLA)

[twassman]

Tests are pending me figuring out how to correctly mock room membership. In the not-unlikely event that someone knows how to do this, assistance would be welcome.

[florianduros]

Tests are pending me figuring out how to correctly mock room membership. In the not-unlikely event that someone knows how to do this, assistance would be welcome.

Hi sorry for the delay!

You can use https://github.com/element-hq/element-web/blob/e97de7d2ea1172e9c11ed604afdf3864bc2fb519/test/test-utils/test-utils.ts#L473 to create a room membership event.

Or you can also mock the membership of the room with: jest.spyOn(room, "getMyMembership").mockReturnValue(KnownMembership.Join);

[twassman]

Thank you! I'll take a look and see if I can implement this.

[twassman]

Apparently all that was necessary was to mock the source room. This should be sufficient?

[t3chguy]

@twassman can you update the PR title to something helpful in a changelog, Recalculate mentions of forwarded messages means nothing to a user

[twassman]

@t3chguy: Better?

[t3chguy]

Not really? What user impact does this have?

[twassman]

Ostensibly that the correct set of users would get mentioned when receiving such forwarded messages. I'm not sure exactly what would be preferable for title phrasing.