@ervin ping?

Surely asks for a unit test, isn't it? Otherwise totally agree with the fix.

Can you suggest how to unittest this, given that this uses currentDate() ?

Oh right, would better use Utils::DateTime::currentDateTime() or similar. This one is overridable through the env var ZANSHIN_OVERRIDE_DATETIME.

The more I dig into this, the more I think all of my previous commits on the topic of timezones might be wrong.
This whole idea of using UTC everywhere comes from 9e65b991 / https://phabricator.kde.org/D876 which doesn't really tell me much about the reasoning.

As a user, I expect my workday to update at midnight LOCAL TIME, not midnight UTC.
All this code using UTC everywhere is, in fact, just wrong. The proper datetime for midnight (which is when the tasks start) is in local time, not in UTC.

We need to make a decision: if we're only supporting dates, we can simplify all this and use QDate everywhere.
If however we want to support date/times at some point, then we need to stop using UTC everywhere in this code, and use local time instead, since that's what we really mean.

So .... what was the reasoning behind the switch to UTC in https://phabricator.kde.org/D876?

I did both, updating this one to fix what you requested *and* creating a separate patch for the final cleanups (which include kcalcore-version-dependent code which has nothing to do with this bugfix, like very old QEXPECT_FAIL lines).