diff --git a/tests/test_extensions.py b/tests/test_extensions.py
index 4faa8379..752de934 100644
--- a/tests/test_extensions.py
+++ b/tests/test_extensions.py
@@ -146,6 +146,7 @@ def new_pull_distributed(self, vqip, of_type=None, tag="default"):
     assert_dict_almost_equal(vq, node.empty_vqip())
     assert node.tank.storage["volume"] == 5
 
+
 def test_handler_extensions(temp_extension_registry):
     from wsimod.arcs.arcs import Arc
     from wsimod.extensions import (
@@ -165,16 +166,17 @@ def test_handler_extensions(temp_extension_registry):
     # 1. Patch a handler
     @register_node_patch("dummy_node", "pull_check_handler", item="default")
     def dummy_patch(*args, **kwargs):
-        return 'dummy_patch'
-    
+        return "dummy_patch"
+
     # 2. Patch a handler with access to self
     @register_node_patch("dummy_node", "pull_set_handler", item="default", is_attr=True)
     def dummy_patch(self):
         def f(vqip, *args, **kwargs):
             return f"{self.name} - {vqip['volume']}"
+
         return f
-    
+
     apply_patches(model)
 
-    assert node.pull_check() == 'dummy_patch'
-    assert node.pull_set({'volume': 1}) == 'dummy_node - 1'
\ No newline at end of file
+    assert node.pull_check() == "dummy_patch"
+    assert node.pull_set({"volume": 1}) == "dummy_node - 1"