diff --git a/tests/helpers.py b/tests/helpers.py
index 03853ef..e4e04b3 100644
--- a/tests/helpers.py
+++ b/tests/helpers.py
@@ -32,13 +32,23 @@ async def _wait():
 
 
 def respond_to_reports(
-    cmds: list[OpenThermReport] = [], responses: list[str] = []
+    cmds: list[OpenThermReport] | None = None, responses: list[str] | None = None
 ) -> Callable[[OpenThermCommand, str, float | None], str]:
     """
     Respond to PR= commands with test values.
     Override response values by specifying cmds and responses in order.
     """
 
+    if len(cmds) != len(responses):
+        raise ValueError(
+            "There should be an equal amount of provided cmds and responses"
+        )
+
+    if cmds is None:
+        cmds = []
+    if responses is None:
+        responses = []
+
     default_responses = {
         OpenThermReport.ABOUT: "A=OpenTherm Gateway 5.8",
         OpenThermReport.BUILD: "B=17:52 12-03-2023",
@@ -58,11 +68,6 @@ def respond_to_reports(
         OpenThermReport.DHW: "W=1",
     }
 
-    if len(cmds) != len(responses):
-        raise ValueError(
-            "There should be an equal amount of provided cmds and responses"
-        )
-
     for cmd, response in zip(cmds, responses):
         if cmd not in default_responses:
             raise ValueError(f"Command {cmd} not found in default responses.")
diff --git a/tests/test_commandprocessor.py b/tests/test_commandprocessor.py
index b946faa..553dbe0 100644
--- a/tests/test_commandprocessor.py
+++ b/tests/test_commandprocessor.py
@@ -149,7 +149,8 @@ async def test_issue_cmd(caplog, pygw_proto):
         (
             "pyotgw.commandprocessor",
             logging.WARNING,
-            f"Command {OpenThermCommand.CONTROL_SETPOINT_2} failed with InvalidCommand, retrying...",
+            f"Command {OpenThermCommand.CONTROL_SETPOINT_2} failed with InvalidCommand,"
+            " retrying...",
         ),
     ]
     caplog.clear()
@@ -185,12 +186,14 @@ async def test_issue_cmd(caplog, pygw_proto):
         (
             "pyotgw.commandprocessor",
             logging.WARNING,
-            f"Command {OpenThermCommand.CONTROL_HEATING_2} failed with Error 03, retrying...",
+            f"Command {OpenThermCommand.CONTROL_HEATING_2} failed with Error 03,"
+            " retrying...",
         ),
         (
             "pyotgw.commandprocessor",
             logging.WARNING,
-            f"Command {OpenThermCommand.CONTROL_HEATING_2} failed with {OpenThermCommand.CONTROL_HEATING_2}: BV, retrying...",
+            f"Command {OpenThermCommand.CONTROL_HEATING_2} failed with"
+            f" {OpenThermCommand.CONTROL_HEATING_2}: BV, retrying...",
         ),
     ]