diff --git a/test/common.py b/test/common.py
index fb86083b3bb37b4ee0906aebb01d110603070c19..472c81a27943fd35fa8543a2c6e970ecfe3b4638 100644
--- a/test/common.py
+++ b/test/common.py
@@ -27,6 +27,10 @@ TESTFLAGGER = (
 )
 
 
+def dummyRegisterFunc(data, field, flagger, kwarg, **kwargs):
+    return data, flagger
+
+
 def initData(cols=2, start_date="2017-01-01", end_date="2017-12-31", freq="1h"):
     dates = pd.date_range(start=start_date, end=end_date, freq=freq)
     data = {}
diff --git a/test/core/test_evaluator.py b/test/core/test_evaluator.py
index d5885e2a8e640158e518a14b2b9c6e8aacd41f9f..a6ea1801a38efc693172a35f4c04738cc5aae163 100644
--- a/test/core/test_evaluator.py
+++ b/test/core/test_evaluator.py
@@ -13,7 +13,7 @@ from saqc.core.evaluator import (
     MetaTransformer,
 )
 
-from test.common import TESTFLAGGER
+from test.common import TESTFLAGGER, dummyRegisterFunc
 
 
 def compileExpression(expr, flagger, nodata=np.nan):
@@ -24,10 +24,6 @@ def compileExpression(expr, flagger, nodata=np.nan):
     return code
 
 
-def _dummyFunc(data, field, flagger, kwarg, **kwargs):
-    pass
-
-
 @pytest.mark.parametrize("flagger", TESTFLAGGER)
 def test_syntaxError(flagger):
     exprs = [
@@ -44,8 +40,8 @@ def test_syntaxError(flagger):
 @pytest.mark.parametrize("flagger", TESTFLAGGER)
 def test_typeError(flagger):
 
-    register("func")(_dummyFunc)
-    register("otherFunc")(_dummyFunc)
+    register("func")(dummyRegisterFunc)
+    register("otherFunc")(dummyRegisterFunc)
 
     exprs = [
         # "func",
@@ -66,8 +62,8 @@ def test_typeError(flagger):
 def test_supportedArguments(flagger):
 
 
-    register("func")(_dummyFunc)
-    register("otherFunc")(_dummyFunc)
+    register("func")(dummyRegisterFunc)
+    register("otherFunc")(dummyRegisterFunc)
 
     exprs = [
         "func(kwarg='str')",