This project is a foobar2000 component, which exposes a RPC interface for a part of foobar2000's internal API. This is similar in nature to foo_com_automation, although based on different technologies.
The built DLL is going to be copied in a local directory, where it expects
a similar structure with the foobar2000's portable installation, the directory
being portable_test\components.
If you don't have this location already existing, you can omit the post build
step with /p:PostBuildEventUseInBuild=false.