diff --git a/passbook/lib/config.py b/passbook/lib/config.py
index a4fc94887..73479ebe6 100644
--- a/passbook/lib/config.py
+++ b/passbook/lib/config.py
@@ -34,7 +34,6 @@ class ConfigLoader:
     loaded_file = []
 
     __config = {}
-    __sub_dicts = []
 
     def __init__(self):
         super().__init__()
@@ -129,12 +128,12 @@ class ConfigLoader:
             self.update(self.__config, outer)
 
     @contextmanager
-    # pylint: disable=invalid-name
-    def cd(self, sub: str):
-        """Contextmanager that descends into sub-dict. Can be chained."""
-        self.__sub_dicts.append(sub)
+    def patch(self, path: str, value: Any):
+        """Context manager for unittests to patch a value"""
+        original_value = self.y(path)
+        self.y_set(path, value)
         yield
-        self.__sub_dicts.pop()
+        self.y_set(path, original_value)
 
     @property
     def raw(self) -> dict:
@@ -146,8 +145,6 @@ class ConfigLoader:
         """Access attribute by using yaml path"""
         # Walk sub_dicts before parsing path
         root = self.raw
-        for sub in self.__sub_dicts:
-            root = root.get(sub, None)
         # Walk each component of the path
         for comp in path.split(sep):
             if root and comp in root:
@@ -156,6 +153,18 @@ class ConfigLoader:
                 return default
         return root
 
+    def y_set(self, path: str, value: Any, sep="."):
+        """Set value using same syntax as y()"""
+        # Walk sub_dicts before parsing path
+        root = self.raw
+        # Walk each component of the path
+        path_parts = path.split(sep)
+        for comp in path_parts[:-1]:
+            if comp not in root:
+                root[comp] = {}
+            root = root.get(comp)
+        root[path_parts[-1]] = value
+
     def y_bool(self, path: str, default=False) -> bool:
         """Wrapper for y that converts value into boolean"""
         return str(self.y(path, default)).lower() == "true"
diff --git a/passbook/outposts/tests.py b/passbook/outposts/tests.py
index 1c1b397ba..019129915 100644
--- a/passbook/outposts/tests.py
+++ b/passbook/outposts/tests.py
@@ -1,13 +1,13 @@
 """outpost tests"""
 from os import environ
 from unittest.case import skipUnless
-from unittest.mock import patch
 
 from django.test import TestCase
 from guardian.models import UserObjectPermission
 
 from passbook.crypto.models import CertificateKeyPair
 from passbook.flows.models import Flow
+from passbook.lib.config import CONFIG
 from passbook.outposts.controllers.k8s.base import NeedsUpdate
 from passbook.outposts.controllers.k8s.deployment import DeploymentReconciler
 from passbook.outposts.controllers.kubernetes import KubernetesController
@@ -104,7 +104,7 @@ class OutpostKubernetesTests(TestCase):
                 deployment_reconciler.get_reference_object(),
             )
 
-        with patch.object(deployment_reconciler, "image_base", "test"):
+        with CONFIG.patch("outposts.docker_image_base", "test"):
             with self.assertRaises(NeedsUpdate):
                 deployment_reconciler.reconcile(
                     deployment_reconciler.retrieve(),