nixVersions: give unit tests access to a $HOME directory

Also, don't try to access cache.nixos.org in the libstore unit tests.
We have to disable the test in versions prior to 2.31; that's OK, since
it was being skipped when run under Nix anyway before that.

(cherry picked from commit 01388b3e78582553cc30ee772db5b5aba8d89edd)

Co-authored-by: Philip Taron <[e-mail]>

pkgs/tools/package-management/nix/modular/src/libflake-tests/package.nix

···
           {
             meta.broken = !stdenv.hostPlatform.emulatorAvailable buildPackages;
           }
-          (
-            lib.optionalString stdenv.hostPlatform.isWindows ''
-              export HOME="$PWD/home-dir"
-              mkdir -p "$HOME"
-            ''
-            + ''
-              export _NIX_TEST_UNIT_DATA=${resolvePath ./data}
-              export NIX_CONFIG="extra-experimental-features = flakes"
-              ${stdenv.hostPlatform.emulator buildPackages} ${lib.getExe finalAttrs.finalPackage}
-              touch $out
-            ''
-          );
+          (''
+            export _NIX_TEST_UNIT_DATA=${resolvePath ./data}
+            export NIX_CONFIG="extra-experimental-features = flakes"
+            export HOME="$TMPDIR/home"
+            mkdir -p "$HOME"
+            ${stdenv.hostPlatform.emulator buildPackages} ${lib.getExe finalAttrs.finalPackage}
+            touch $out
+          '');
     };
   };
 

pkgs/tools/package-management/nix/modular/src/libstore-tests/package.nix

···
   mesonFlags = [
   ];
 
+  excludedTestPatterns = lib.optionals (lib.versionOlder finalAttrs.version "2.31") [
+    "nix_api_util_context.nix_store_real_path_binary_cache"
+  ];
+
   passthru = {
     tests = {
       run =
···
           {
             meta.broken = !stdenv.hostPlatform.emulatorAvailable buildPackages;
           }
-          (
-            lib.optionalString stdenv.hostPlatform.isWindows ''
-              export HOME="$PWD/home-dir"
-              mkdir -p "$HOME"
-            ''
-            + ''
-              export _NIX_TEST_UNIT_DATA=${data + "/src/libstore-tests/data"}
-              ${stdenv.hostPlatform.emulator buildPackages} ${lib.getExe finalAttrs.finalPackage}
-              touch $out
-            ''
-          );
+          (''
+            export _NIX_TEST_UNIT_DATA=${data + "/src/libstore-tests/data"}
+            export HOME="$TMPDIR/home"
+            mkdir -p "$HOME"
+            ${stdenv.hostPlatform.emulator buildPackages} ${lib.getExe finalAttrs.finalPackage} \
+              --gtest_filter=-${lib.concatStringsSep ":" finalAttrs.excludedTestPatterns}
+            touch $out
+          '');
     };
   };