chore: better solution for handling store paths in variables

lib/impl/jobPatched.nix

@@ -11,21 +11,33 @@ in
     pipelineName,
     nixConfig,
   }:
-    job
+    (builtins.removeAttrs job ["variables" "cache"])
     // (optionalAttrs nixConfig.enable (
       (prependToBeforeScript ["source setup_nix_ci \"gitlab-ci:pipeline:${pipelineName}:job-deps:${key}\""] job)
       // (appendToAfterScript ["finalize_nix_ci"] job)
     ))
-    // optionalAttrs nixConfig.enable {
-      variables =
-        (filterJobVariables false job)
-        // optionalAttrs nixConfig.enableRunnerCache {
-          NIX_CI_CACHE_STRATEGY = "runner";
-        };
-      cache =
-        (toList (job.cache or []))
-        ++ (optional nixConfig.enableRunnerCache {
-          key = nixConfig.runnerCacheKey;
-          paths = [".nix-cache/"];
-        });
-    }
+    // optionalAttrs nixConfig.enable (
+      (let
+        variables =
+          (filterJobVariables false job)
+          // optionalAttrs nixConfig.enableRunnerCache {
+            NIX_CI_CACHE_STRATEGY = "runner";
+          };
+      in
+        # filter empty variables
+        optionalAttrs (variables != {}) {
+          inherit variables;
+        })
+      // (let
+        cache =
+          (toList (job.cache or []))
+          ++ (optional nixConfig.enableRunnerCache {
+            key = nixConfig.runnerCacheKey;
+            paths = [".nix-cache/"];
+          });
+      in
+        # filter empty cache
+        optionalAttrs (cache != []) {
+          inherit cache;
+        })
+    )

tests/cilib_test.nix

@@ -148,10 +148,7 @@
         name = "handle store paths in variables";
         expected = {
           stages = ["test"];
-          test = {
-            stage = "test";
-            variables."TEST" = "${pkgs.hello}";
-          };
+          test.stage = "test";
         };
         actual =
           (mkPipeline {