Unit test failing with Expected event "DelegateVotesChanged" to be emitted, but it wasn't

[michalinacienciala]

Nightly unit tests of threshold-network/solidity-contracts have failed one time lately with the following error:

  1) T token
       burn
         when delegated to someone else
           should emit DelegateVotesChanged:
     AssertionError: Expected event "DelegateVotesChanged" to be emitted, but it wasn't

Failing workflow: https://github.com/threshold-network/solidity-contracts/runs/7050777498?check_suite_focus=true

That's the first time I see such failure. When re-run, the workflow has passed, executions on other days were also successful. Although it's the only time I see this this test failing, it doesn't seem to me like a test that could randomly fail due to some 3rd party component temporary unavailability. It's probably some synchronization problem in the unit test - missing await or something similar. Needs to be investigated.