tests: Add simple tests for nix-shell

nix-shell -A, -p and -i are lightly tested.

tests/local.mk

@@ -11,7 +11,7 @@ nix_tests = \
   multiple-outputs.sh import-derivation.sh fetchurl.sh optimise-store.sh \
   binary-cache.sh nix-profile.sh repair.sh dump-db.sh case-hack.sh \
   check-reqs.sh pass-as-file.sh tarball.sh restricted.sh \
-  placeholders.sh
+  placeholders.sh nix-shell.sh
   # parallel.sh
 
 install-tests += $(foreach x, $(nix_tests), tests/$(x))

tests/nix-shell.sh

@@ -0,0 +1,21 @@
+source common.sh
+
+clearStore
+
+# Test nix-shell -A
+export IMPURE_VAR=foo
+output=$(nix-shell --pure shell.nix -A shellDrv --run \
+    'echo "$IMPURE_VAR - $VAR_FROM_STDENV_SETUP - $VAR_FROM_NIX"')
+
+[ "$output" = " - foo - bar" ]
+
+# Test nix-shell -p
+output=$(NIX_PATH=nixpkgs=shell.nix nix-shell --pure -p foo bar --run 'echo "$(foo) $(bar)"')
+[ "$output" = "foo bar" ]
+
+# Test nix-shell shebang mode
+sed -e "s|@ENV_PROG@|$(type -p env)|" shell.shebang.sh > $TEST_ROOT/shell.shebang.sh
+chmod a+rx $TEST_ROOT/shell.shebang.sh
+
+output=$($TEST_ROOT/shell.shebang.sh)
+[ "$output" = "foo bar" ]

tests/shell.nix

@@ -0,0 +1,46 @@
+{ }:
+
+with import ./config.nix;
+
+rec {
+  setupSh = builtins.toFile "setup" ''
+    export VAR_FROM_STDENV_SETUP=foo
+    for pkg in $buildInputs; do
+      export PATH=$PATH:$pkg/bin
+    done
+  '';
+
+  stdenv = mkDerivation {
+    name = "stdenv";
+    buildCommand = ''
+      mkdir -p $out
+      ln -s ${setupSh} $out/setup
+    '';
+  };
+
+  shellDrv = mkDerivation {
+    name = "shellDrv";
+    builder = "/does/not/exist";
+    VAR_FROM_NIX = "bar";
+    inherit stdenv;
+  };
+
+  # Used by nix-shell -p
+  runCommand = name: args: buildCommand: mkDerivation (args // {
+    inherit name buildCommand stdenv;
+  });
+
+  foo = runCommand "foo" {} ''
+    mkdir -p $out/bin
+    echo 'echo foo' > $out/bin/foo
+    chmod a+rx $out/bin/foo
+  '';
+
+  bar = runCommand "bar" {} ''
+    mkdir -p $out/bin
+    echo 'echo bar' > $out/bin/bar
+    chmod a+rx $out/bin/bar
+  '';
+
+  bash = shell;
+}

tests/shell.shebang.sh

@@ -0,0 +1,4 @@
+#! @ENV_PROG@ nix-shell
+#! nix-shell -I nixpkgs=shell.nix --option use-binary-caches false
+#! nix-shell --pure -i bash -p foo bar
+echo "$(foo) $(bar)"