diff --git a/test/fixtures/server.py b/test/fixtures/server.py
index e7c77b4..d1d0a96 100644
--- a/test/fixtures/server.py
+++ b/test/fixtures/server.py
@@ -12,7 +12,7 @@ from waitress import serve
 
 from pyinfra.rest import wrap_operation
 from pyinfra.utils.buffer import bufferize
-from pyinfra.utils.func import lift, llift
+from pyinfra.utils.func import llift
 from test.server import set_up_processing_server
 from test.utils.image import image_to_bytes
 
@@ -45,17 +45,16 @@ def server(processor_fn):
 
 @pytest.fixture
 def processor_fn(operation, buffer_size, batched):
-
-    fn = wrap_operation(operation)
+    operation = wrap_operation(operation)
 
     if not batched:
-        fn = llift(fn)
+        operation = llift(operation)
 
-    return bufferize(fn, buffer_size=buffer_size, persist_fn=attrgetter("json"))
+    return bufferize(operation, buffer_size=buffer_size, persist_fn=attrgetter("json"))
 
 
 @pytest.fixture
-def operation(item_type):
+def operation(item_type, batched):
     def upper(string: bytes, metadata):
         return string.decode().upper().encode(), metadata
 
@@ -68,14 +67,16 @@ def operation(item_type):
             yield page.get_pixmap().tobytes("png"), metadata
 
     if item_type == "string":
-        return upper
+        operation = upper
     elif item_type == "image":
-        return rotate
+        operation = rotate
     elif item_type == "pdf":
-        return stream_pages
+        operation = stream_pages
     else:
         raise ValueError(f"No operation specified for item type {item_type}")
 
+    return operation
+
 
 @pytest.fixture(params=["string"])
 def item_type(request):
@@ -87,6 +88,7 @@ def batched(request):
     """Controls, whether the buffer processor function of the webserver is applied to batches or single items."""
     return request.param
 
+
 @pytest.fixture(params=[1, 3, 7, 100])
 def buffer_size(request):
     return request.param