tests: Add tests for the shellFor function

test/default.nix

@@ -17,6 +17,7 @@ in {
   builder-haddock = haskell.callPackage ./builder-haddock {};
   stack-simple = haskell.callPackage ./stack-simple {};
   snapshots = haskell.callPackage ./snapshots {};
+  shell-for = haskell.callPackage ./shell-for {};
   callStackToNix = haskell.callPackage ./callStackToNix {};
   callCabalProjectToNix = haskell.callPackage ./call-cabal-project-to-nix {};
 

test/regen.nix

@@ -57,4 +57,9 @@ writeScript "regen-tests.sh" ''
   cd stack-simple
   stack-to-nix -o .
   cd ..
+
+  cd shell-for
+  cabal_configure
+  plan-to-nix -o . --plan-json dist-newstyle/cache/plan.json --cabal-project cabal.project
+  cd ..
 ''

test/shell-for/conduit.hs

@@ -0,0 +1,19 @@
+-- https://github.com/snoyberg/conduit#readme
+
+import Conduit
+import System.Directory (removeFile)
+
+main = do
+    -- Pure operations: summing numbers.
+    print $ runConduitPure $ yieldMany [1..10] .| sumC
+
+    -- Exception safe file access: copy a file.
+    writeFile "input.txt" "This is a test." -- create the source file
+    runConduitRes $ sourceFileBS "input.txt" .| sinkFile "output.txt" -- actual copying
+    readFile "output.txt" >>= putStrLn -- prove that it worked
+
+    -- Perform transformations.
+    print $ runConduitPure $ yieldMany [1..10] .| mapC (+ 1) .| sinkList
+
+    removeFile "input.txt"
+    removeFile "output.txt"

test/shell-for/default.nix

@@ -0,0 +1,52 @@
+{ stdenv, cabal-install, mkCabalProjectPkgSet }:
+
+with stdenv.lib;
+
+let
+  pkgSet = mkCabalProjectPkgSet {
+    plan-pkgs = import ./pkgs.nix;
+    pkg-def-extras = [{
+      pkga = ./.plan.nix/pkga.nix;
+      pkgb = ./.plan.nix/pkgb.nix;
+    }];
+    modules = [{
+      # Package has no exposed modules which causes
+      #   haddock: No input file(s)
+      packages.bytestring-builder.doHaddock = false;
+    }];
+  };
+
+  env = pkgSet.config.hsPkgs.shellFor {
+    # Shell will provide the dependencies of pkga and pkgb, but not
+    # pkga and pkgb themselves.
+    packages = ps: with ps; [ pkga pkgb ];
+    # This adds cabal-install to the shell, which helps tests because
+    # they use a nix-shell --pure. Normally you would BYO cabal-install.
+    buildInputs = [ cabal-install ];
+  };
+
+in
+  stdenv.mkDerivation {
+    name = "shell-for-test";
+
+    buildCommand = ''
+      ########################################################################
+      # test shell-for with an example program
+
+      cp ${./pkgb/src}/*.hs .
+
+      printf "checking that the shell env has the dependencies...\n" >& 2
+      ${env.ghc}/bin/runghc conduit.hs
+
+      touch $out
+    '';
+
+    meta.platforms = platforms.all;
+    passthru = {
+      # Used for debugging with nix repl
+      inherit pkgSet;
+
+      # Used for testing externally with nix-shell (../tests.sh).
+      inherit env;
+    };
+}

test/tests.sh

@@ -54,4 +54,11 @@ nix-shell $NIX_BUILD_ARGS \
     --run 'cd cabal-simple && cabal new-build'
 echo >& 2
 
+printf "*** Checking shellFor works for a cabal project...\n" >& 2
+nix-shell $NIX_BUILD_ARGS \
+    --pure ./default.nix \
+    -A shell-for.env \
+    --run 'cd shell-for && cabal new-build all'
+echo >& 2
+
 printf "\n*** Finished successfully\n" >& 2