nix-shell+Haskell+cabal requires test-suite?

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1

I’m using NixOS 21.05. I have a directory with just the following two files:

$ cat default.nix
let 
  pkgs = import <nixpkgs> { };
in 
  pkgs.haskellPackages.developPackage {
    root = ./.;
    modifier = drv:
      pkgs.haskell.lib.addBuildTools drv (with pkgs.haskellPackages;
        [ cabal-install
        ]);
  }

$ cat amy-test.cabal
cabal-version:      2.4
name:               amy-test
version:            1.0

library
  exposed-modules:  MyLib
  build-depends:    base >=4.7 && <5
  hs-source-dirs:   src
  default-language: Haskell2010

-- -- UNCOMMENT THIS BLOCK AND nix-shell SUCCEEDS
-- test-suite gray-extended-test
--   default-language: Haskell2010
--   type:             exitcode-stdio-1.0
--   hs-source-dirs:   test
--   main-is:          TestMain.hs
--   build-depends:
--     , base
--     , gray-extended
--     , test-framework

If I invoke nix-shell without a test-suite section in the cabal file, I get an error:

$ nix-shell --show-trace
error: while evaluating the attribute 'NIX_GHC' of the derivation 'ghc-shell-for-amy-test-1.0' at /nix/store/g2bm5amvm77m4w9gbf5g1wzbw22hyam2-nixos-21.05.1669.973910f5c31/nixos/pkgs/stdenv/generic/make-derivation.nix:201:11:
while evaluating the attribute 'paths' of the derivation 'ghc-8.10.4-with-packages' at /nix/store/g2bm5amvm77m4w9gbf5g1wzbw22hyam2-nixos-21.05.1669.973910f5c31/nixos/pkgs/stdenv/generic/make-derivation.nix:201:11:
while evaluating the attribute 'buildCommand' of the derivation 'hoogle-local-0.1' at /nix/store/g2bm5amvm77m4w9gbf5g1wzbw22hyam2-nixos-21.05.1669.973910f5c31/nixos/pkgs/stdenv/generic/make-derivation.nix:201:11:
while evaluating 'optionalString' at /nix/store/g2bm5amvm77m4w9gbf5g1wzbw22hyam2-nixos-21.05.1669.973910f5c31/nixos/lib/strings.nix:202:5, called from /nix/store/g2bm5amvm77m4w9gbf5g1wzbw22hyam2-nixos-21.05.1669.973910f5c31/nixos/pkgs/development/haskell-modules/hoogle.nix:66:7:
while evaluating 'concatMapStringsSep' at /nix/store/g2bm5amvm77m4w9gbf5g1wzbw22hyam2-nixos-21.05.1669.973910f5c31/nixos/lib/strings.nix:110:5, called from /nix/store/g2bm5amvm77m4w9gbf5g1wzbw22hyam2-nixos-21.05.1669.973910f5c31/nixos/pkgs/development/haskell-modules/hoogle.nix:69:10:
while evaluating anonymous function at /nix/store/g2bm5amvm77m4w9gbf5g1wzbw22hyam2-nixos-21.05.1669.973910f5c31/nixos/pkgs/development/haskell-modules/hoogle.nix:69:40, called from undefined position:
value is null while a set was expected, at /nix/store/g2bm5amvm77m4w9gbf5g1wzbw22hyam2-nixos-21.05.1669.973910f5c31/nixos/pkgs/development/haskell-modules/hoogle.nix:69:43

However, if I add a test suite section (uncommenting it in the cabal file), nix-shell succeeds. Is this a bug, or is there something I don’t understand about nix? I normally do have test-suite sections in all my cabal files, but I ran into this issue while trying to debug another problem.

2

This is likely a bug.

You shouldn’t need a test-suite section in your cabal file in order to use developPackage.

We’d be happy to accept a PR fixing this (or even just an issue created in the nixpkgs repo).

1 Like
3

Thank you. Bug filed: developPackage requires a test-suite · Issue #131744 · NixOS/nixpkgs · GitHub

1 Like