This seems relevant:

Starting test execution, please wait...
A total of 1 test files matched the specified pattern.
[xUnit.net 00:00:00.00] xUnit.net VSTest Adapter v2.8.2+699d445a1a (64-bit .NET 9.0.6)
[xUnit.net 00:00:00.11]   Discovering: NexusMods.Games.RedEngine.Tests
[xUnit.net 00:00:00.19]   Discovered:  NexusMods.Games.RedEngine.Tests
[xUnit.net 00:00:00.19]   Starting:    NexusMods.Games.RedEngine.Tests
  Passed NexusMods.Games.RedEngine.Tests.Cyberpunk2077SynchronizerTests.ContentIsIgnoredWhenSettingIsSet [102 ms]
  Passed NexusMods.Games.RedEngine.Tests.Cyberpunk2077DiagnosticTests.CyberpunkGameExposesPatternBasedDiagnostics [106 ms]
The active test run was aborted. Reason: Test host process crashed

Test Run Aborted.
Total tests: Unknown
     Passed: 2
 Total time: 2.3107 Seconds
  The "VSTestTask" task returned false but did not log an error. (TaskId:381)
Done executing task "VSTestTask" -- FAILED. (TaskId:381)
Done building target "_VSTestConsole" in project "NexusMods.Games.RedEngine.Tests.csproj" -- FAILED.: (TargetId:99)
Done executing task "CallTarget" -- FAILED. (TaskId:361)
Done building target "VSTest" in project "NexusMods.Games.RedEngine.Tests.csproj" -- FAILED.: (TargetId:98)

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?

I'm wondering if it is practical to move the tests into a passthru.tests derivation 🤔

That way 1) end-users wouldn't need to run the tests to build the unfree package, 2) intermittent tests wouldn't cause build failures on hydra.

I'd still like to uncover the actual issue, but I'm curious if extracting the tests to a separate derivation is possible?

I guess the test derivation would need the same src as the main package, to access the test cases and relevant build properties. It'd also need the main package as an input, to get the built binaries.

That sounds reasonable, but what I'm unsure of is how easy it'd be to tell dotnet test to run the local test cases against the pre-built binaries from the main package?

Maybe I'll see if I can find anything useful in VSTestTask

Looks like the impl is here: https://github.com/dotnet/dotnet/blob/main/src/vstest/src/Microsoft.TestPlatform.Build/Tasks/VSTestTask.cs

There's a note about the "Task returned false but did not log an error." error at line 69.

Other than that, I nothing is jumping out at me 🤔

Also: I noticed that the Test host process crashed and "VSTestTask" task returned false but did not log an error. errors also appear in normal (failing) build logs, even without -v:diag. We just need to scroll up to find them, as they're usually not at the end of the logs.