my usual thing is

nix develop -f. nexusmods-app
cd $NIX_BUILD_TOP
genericBuild

the problem with that is that it won't stop on errors, so it'll try to run all the phases, which may or may not be a problem. at the end you can do runPhase checkPhase

Looking around, it seems vtest has a thread discussing a similar Test host process crashed error. In that instance, it turned out to be an out-of-memory error.

Is there an easy way to tell the package to run time -v dotnet test instead of simply dotnet test?

If it turns out to be a memory issue, is there a way to increase dotnet test's available memory, or should we just disable RAM-intensive tests?

If it was out of memory it would have to be using a lot of memory to be reproducible on my desktop machine.

Good point, I have 64GB and was reproducing the issue fairly regularly. I take it there's no artificial memory limit from dotnet or the build sandbox?

Maybe it's hitting a file handle ulimit or something?

Could be something like that. Or could just be random segfaults in buggy software... 🤔

It would be nice to know more about the child process invocation (args, output, exit code).

Anything specific you want me to test, other than just time -v?