When running tests in parallel, log output related to one test will leak into other test output

[pseudobjorn]

I am writing integration tests for a .NET Core 2.1 project (web api). I am using the latest version of all nuget packages (.net, xunit, serilog, etc). I have recently switched to serilog as the logging engine for my web api, and this works fine. However, in my integration tests, I thought it would be nice to see the logg-statements from the TestServer in the XUnit output window. In order to achieve this, I installed your nuget package, and created a logger as per your documentation.

This works perfectly fine, as long as I run a single test at a time. I can see the log statements that I trigger directly from my test-methods, as well as the log statements triggered within the actual webhost.

However, if I try to run all the tests in one go (XUnit will do this in parallell), the output from one test is leaked into the output for another! This makes sense to me, since Log.Logger after all is a globally shared logger.

Other Serilog sinks exist for xunit, and I see that a similar issue have been reported there, for example: https://github.com/davetimmins/serilog-sinks-xunittestoutput/issues/6

Are you able to reproduce this behaviour? It would be great if you could look into this!

[trbenning]

Thanks for reporting this. I'll look into it this weekend.

[pseudobjorn]

Hi Todd, any news on this?

[TysonMN]

This makes sense to me, since Log.Logger after all is a globally shared logger.

That is your issue. If your tests log to the global/static logger, then you will have race conditions that determine where the log events go.

To avoid this, you need to inject instance-specific Iloggers and send your log events to them instead.

[trbenning]

Functions as designed