Comment 22 for bug 1804513

> The issues mentioned to be caused by the 'buggy' version do seem to be high-impact, but from what I understand the application is still usable - is that correct?

It depends on the definition of usable. You can start the application play tracks, but it may stop a party, which is the most critical bug we can think of. We actually do not know the effects very well, because the cosmic build linked with Qt5 has bypassed our quality management. The Mixxx 2.1.3 was tested and released with Qt4.8 only. It is strongly recommended to not use this build because of that.

> Looking at the source, it looks to me that there is quite a lot of unit-tests defined - are those being run during build time?

Most unit tests are unit testing against regressions inside the audio engine. The tests are linked in a own binary, not the production binary build on Launchpad, so we cannot detect link and packaging issues like we face here. We execute them automatically in each PR and before release on our own CI.

But IMHO the situation is way better now, thanks to the delay here: Mixxx 2.2.0 was released on 11th January, almost 6 month ago and it has landed in various distros without mayor complains:
https://repology.org/project/mixxx/versions

> Finally, if we decide to include this SRU in our stable series, the manual testing story will have to be improved.

Yes, some "smoke tests" with the production binary should be done help such situation is not repeated.

I will update the test cases and the linked bugs.