Test(InventoryPersistence): add persist integration tests

pkgs/clan-cli/clan_lib/persist/fixtures/1.json

@@ -0,0 +1 @@
+{}

pkgs/clan-cli/clan_lib/persist/fixtures/1.nix

@@ -0,0 +1,29 @@
+{ clanLib, lib, ... }:
+let
+  eval = lib.evalModules {
+    modules = [
+      {
+        # Trying to write into the default
+        options.foo = lib.mkOption {
+          type = lib.types.str;
+          default = "bar";
+        };
+        options.protected = lib.mkOption {
+          type = lib.types.str;
+        };
+      }
+      {
+        # Cannot write into the default set prio
+        protected = "protected";
+      }
+      # Merge the "inventory.json"
+      (builtins.fromJSON (builtins.readFile ./1.json))
+    ];
+  };
+in
+{
+  clanInternals.inventoryClass.inventory = eval.config;
+  clanInternals.inventoryClass.introspection = clanLib.introspection.getPrios {
+    options = eval.options;
+  };
+}