Extracting test binaries

[TheNeikos]

I am currently writing some tests that require the docker daemon to work, hence I cannot run them inside the nix sandbox. My idea was to use buildPackage with cargoExtraArgs = "--tests" so that it would also build the tests and hopefully also extract them. Then I could run them manually from the outside.

Sadly, that did not work, the output derivation was simply empty. The next problem is also, that test binaries have a checksum in them, so I cannot hardcode extract them either.

Is there anything from the great toolset that crane provides that would get me close to that goal?

[ipetkov]

I would suggest adapting what buildPackage does for extracting the test binaries:

1. Run the cargo test --no-run --message-format json-render-diagnostics and capture the logs (example)
2. Use jq to filter the binaries you care about. buildPackage ignores tests and only looks for libraries or other executables but you might be able to achieve it with a filter like 'select(.reason == "compiler-artifact" and .profile.test == true) | .executable' (you may need to tweak it further to suit your needs but from a quick test it looks like it will achieve what you are looking for)
3. The jq output will provide all the test binaries which would have been run for this test, and they can be copied/installed as appropriate

Hope this helps!

[TheNeikos]

That worked exactly as you wrote it down. Thank you very much!