lib/tests/test-with-nix.nix: init

See https://github.com/NixOS/nix/pull/9900

lib/tests/release.nix

@@ -9,60 +9,7 @@
 let
   lib = import ../.;
   testWithNix = nix:
-    pkgs.runCommand "nixpkgs-lib-tests-nix-${nix.version}" {
+    import ./test-with-nix.nix { inherit lib nix pkgs; };
-      buildInputs = [
-        (import ./check-eval.nix)
-        (import ./maintainers.nix {
-          inherit pkgs;
-          lib = import ../.;
-        })
-        (import ./teams.nix {
-          inherit pkgs;
-          lib = import ../.;
-        })
-        (import ../path/tests {
-          inherit pkgs;
-        })
-      ];
-      nativeBuildInputs = [
-        nix
-        pkgs.gitMinimal
-      ] ++ lib.optional pkgs.stdenv.isLinux pkgs.inotify-tools;
-      strictDeps = true;
-    } ''
-      datadir="${nix}/share"
-      export TEST_ROOT=$(pwd)/test-tmp
-      export HOME=$(mktemp -d)
-      export NIX_BUILD_HOOK=
-      export NIX_CONF_DIR=$TEST_ROOT/etc
-      export NIX_LOCALSTATE_DIR=$TEST_ROOT/var
-      export NIX_LOG_DIR=$TEST_ROOT/var/log/nix
-      export NIX_STATE_DIR=$TEST_ROOT/var/nix
-      export NIX_STORE_DIR=$TEST_ROOT/store
-      export PAGER=cat
-      cacheDir=$TEST_ROOT/binary-cache
-
-      nix-store --init
-
-      cp -r ${../.} lib
-      echo "Running lib/tests/modules.sh"
-      bash lib/tests/modules.sh
-
-      echo "Running lib/tests/filesystem.sh"
-      TEST_LIB=$PWD/lib bash lib/tests/filesystem.sh
-
-      echo "Running lib/tests/sources.sh"
-      TEST_LIB=$PWD/lib bash lib/tests/sources.sh
-
-      echo "Running lib/fileset/tests.sh"
-      TEST_LIB=$PWD/lib bash lib/fileset/tests.sh
-
-      echo "Running lib/tests/systems.nix"
-      [[ $(nix-instantiate --eval --strict lib/tests/systems.nix | tee /dev/stderr) == '[ ]' ]];
-
-      mkdir $out
-      echo success > $out/${nix.version}
-    '';
 
 in
   pkgs.symlinkJoin {

lib/tests/test-with-nix.nix

@@ -0,0 +1,70 @@
+/**
+ * Instantiate the library tests for a given Nix version.
+ *
+ * IMPORTANT:
+ * This is used by the github.com/NixOS/nix CI.
+ *
+ * Try not to change the interface of this file, or if you need to, ping the
+ * Nix maintainers for help. Thank you!
+ */
+{
+  pkgs,
+  lib,
+  # Only ever use this nix; see comment at top
+  nix,
+}:
+
+pkgs.runCommand "nixpkgs-lib-tests-nix-${nix.version}" {
+  buildInputs = [
+    (import ./check-eval.nix)
+    (import ./maintainers.nix {
+      inherit pkgs;
+      lib = import ../.;
+    })
+    (import ./teams.nix {
+      inherit pkgs;
+      lib = import ../.;
+    })
+    (import ../path/tests {
+      inherit pkgs;
+    })
+  ];
+  nativeBuildInputs = [
+    nix
+    pkgs.gitMinimal
+  ] ++ lib.optional pkgs.stdenv.isLinux pkgs.inotify-tools;
+  strictDeps = true;
+} ''
+  datadir="${nix}/share"
+  export TEST_ROOT=$(pwd)/test-tmp
+  export HOME=$(mktemp -d)
+  export NIX_BUILD_HOOK=
+  export NIX_CONF_DIR=$TEST_ROOT/etc
+  export NIX_LOCALSTATE_DIR=$TEST_ROOT/var
+  export NIX_LOG_DIR=$TEST_ROOT/var/log/nix
+  export NIX_STATE_DIR=$TEST_ROOT/var/nix
+  export NIX_STORE_DIR=$TEST_ROOT/store
+  export PAGER=cat
+  cacheDir=$TEST_ROOT/binary-cache
+
+  nix-store --init
+
+  cp -r ${../.} lib
+  echo "Running lib/tests/modules.sh"
+  bash lib/tests/modules.sh
+
+  echo "Running lib/tests/filesystem.sh"
+  TEST_LIB=$PWD/lib bash lib/tests/filesystem.sh
+
+  echo "Running lib/tests/sources.sh"
+  TEST_LIB=$PWD/lib bash lib/tests/sources.sh
+
+  echo "Running lib/fileset/tests.sh"
+  TEST_LIB=$PWD/lib bash lib/fileset/tests.sh
+
+  echo "Running lib/tests/systems.nix"
+  [[ $(nix-instantiate --eval --strict lib/tests/systems.nix | tee /dev/stderr) == '[ ]' ]];
+
+  mkdir $out
+  echo success > $out/${nix.version}
+''