Stepping through builder steps in your custom packages

This article was originally published at https://gist.github.com/joepie91/b0041188c043259e6e1059d026eff301. 

1. Create a temporary building folder in your repository (or elsewhere) and enter it: mkdir test && cd test
2. nix-shell ../main.nix -A packagename (assuming the entry point for your custom repository is main.nix in the parent directory)
3. Run the phases individually by entering their name (for a default phase) or doing something like eval "$buildPhase" (for an overridden phase) in the Nix shell - a summary of the common ones: unpackPhase, patchPhase, configurePhase, buildPhase, checkPhase, installPhase, fixupPhase, distPhase

More information about these phases can be found here. If you use a different builder, you may have a different set of phases.

Don't forget to clear out your test folder after every attempt!