vars: make all python tests work in nix sandbox

- generate a flake.lock file for each template by copying the clan-core flake.lock and modifying it

- call nix build with --store for tests inside the sandbox

pkgs/clan-cli/clan_cli/machines/inventory.py

@@ -1,4 +1,5 @@
 import json
+import os
 from pathlib import Path
 
 from clan_cli.clan_uri import FlakeId
@@ -16,6 +17,10 @@ def get_all_machines(flake: FlakeId, nix_options: list[str]) -> list[Machine]:
         nix_build([f'{flake}#clanInternals.all-machines-json."{system}"'])
     ).stdout
 
+    tmp_store = os.environ.get("TMP_STORE", None)
+    if tmp_store:
+        json_path = f"{tmp_store}/{json_path}"
+
     machines_json = json.loads(Path(json_path.rstrip()).read_text())
 
     machines = []

pkgs/clan-cli/clan_cli/machines/machines.py

@@ -1,6 +1,7 @@
 import importlib
 import json
 import logging
+import os
 from dataclasses import dataclass, field
 from functools import cached_property
 from pathlib import Path
@@ -329,6 +330,10 @@ class Machine:
             return self._build_cache[attr]
 
         output = self.nix("build", attr, extra_config, nix_options)
+        assert isinstance(output, Path), "Nix build did not result in a single path"
+        tmp_store = os.environ.get("TMP_STORE", None)
+        if tmp_store is not None:
+            output = Path(f"{tmp_store}/{output!s}")
         if isinstance(output, Path):
             self._build_cache[attr] = output
             return output

pkgs/clan-cli/clan_cli/nix/__init__.py

@@ -10,7 +10,11 @@ from clan_cli.errors import ClanError
 
 
 def nix_command(flags: list[str]) -> list[str]:
-    return ["nix", "--extra-experimental-features", "nix-command flakes", *flags]
+    args = ["nix", "--extra-experimental-features", "nix-command flakes", *flags]
+    store = os.environ.get("TMP_STORE", None)
+    if store:
+        args += ["--store", store]
+    return args
 
 
 def nix_flake_show(flake_url: str | Path) -> list[str]: