dotnet test takes 19s, after we do dotnet add package AltCover it takes 1+hour

[amitwats]

When we executed a test execution using dotnet test someProj.csproj the test execution takes 19 seconds. After we add packages with dotnet add package AltCover it takes more than 1 hour.

1. Is this normal?
2. Is there a way to minimise this?

[SteveGilham]

No, that is not normal. While there is necessarily some overhead in the coverage gathering, including needing to serialize the output in multi-threaded situations, I've not observed that factor of slowdown myself.

For example, AltCover's own unit tests take 50s by themselves, but that only increases to 2 minutes when self-instrumenting, and that's including build time.

Can you isolate a simple example of the problem that you can share?

[SteveGilham]

I have made changes in 5.0.665 which have improved the throughput and speeded unit tests for me; however I've not had such a pathological case to work with, si I don't know if it will make any difference for your case.

[SteveGilham]

Release v5.3.675 makes some significant speed-ups for dotnet test cases which have heretofore been limited by the data collection mechanism used to work around vstest.console's hard guillotine at process exit.