diff --git a/mlair/helpers/testing.py b/mlair/helpers/testing.py
index e727d9b50308d339af79f5c5b82b592af6e91921..9820b4956dac09e213df3b9addc317a00ee381b8 100644
--- a/mlair/helpers/testing.py
+++ b/mlair/helpers/testing.py
@@ -105,7 +105,7 @@ def get_all_args(*args, remove=None, add=None):
     return res
 
 
-def test_nested_equality(obj1, obj2):
+def check_nested_equality(obj1, obj2):
 
     try:
         print(f"check type {type(obj1)} and {type(obj2)}")
@@ -116,13 +116,13 @@ def test_nested_equality(obj1, obj2):
             assert len(obj1) == len(obj2)
             for pos in range(len(obj1)):
                 print(f"check pos {obj1[pos]} and {obj2[pos]}")
-                assert test_nested_equality(obj1[pos], obj2[pos]) is True
+                assert check_nested_equality(obj1[pos], obj2[pos]) is True
         elif isinstance(obj1, dict):
             print(f"check keys {obj1.keys()} and {obj2.keys()}")
             assert sorted(obj1.keys()) == sorted(obj2.keys())
             for k in obj1.keys():
                 print(f"check pos {obj1[k]} and {obj2[k]}")
-                assert test_nested_equality(obj1[k], obj2[k]) is True
+                assert check_nested_equality(obj1[k], obj2[k]) is True
         elif isinstance(obj1, xr.DataArray):
             print(f"check xr {obj1} and {obj2}")
             assert xr.testing.assert_equal(obj1, obj2) is None
diff --git a/test/test_helpers/test_filter.py b/test/test_helpers/test_filter.py
index 519a36b3438cafd041cc65c43572fc026eced4dd..6f72eda69f92fced8fde8532b812a3bf340fdc80 100644
--- a/test/test_helpers/test_filter.py
+++ b/test/test_helpers/test_filter.py
@@ -121,22 +121,22 @@ class TestClimateFIRFilter:
             obj._create_tmp_dimension(xr_array)
         assert "Could not create new dimension." in e.value.args[0]
 
-    def test_minimum_length(self):
+    def test_next_order(self):
         obj = object.__new__(ClimateFIRFilter)
-        res = obj._minimum_length([43], 15, 0, "hamming")
+        res = obj._next_order([43], 15, 0, "hamming")
         assert res == 15
-        res = obj._minimum_length([43, 13], 15, 0, ("kaiser", 10))
+        res = obj._next_order([43, 13], 15, 0, ("kaiser", 10))
         assert res == 28
-        res = obj._minimum_length([43, 13], 15, 1, "hamming")
+        res = obj._next_order([43, 13], 15, 1, "hamming")
         assert res == 15
-        res = obj._minimum_length([128, 64, 43], None, 0, "hamming")
+        res = obj._next_order([128, 64, 43], None, 0, "hamming")
         assert res == 64
-        res = obj._minimum_length([43], None, 0, "hamming")
+        res = obj._next_order([43], None, 0, "hamming")
         assert res is None
 
-    def test_minimum_length_with_kzf(self):
+    def test_next_order_with_kzf(self):
         obj = object.__new__(ClimateFIRFilter)
-        res = obj._minimum_length([(15, 5), (5, 3)], None, 0, "kzf")
+        res = obj._next_order([(15, 5), (5, 3)], None, 0, "kzf")
         assert res == 13
 
     def test_calculate_filter_coefficients(self):
@@ -316,7 +316,7 @@ class TestClimateFIRFilter:
         obj = object.__new__(ClimateFIRFilter)
         filter_order = 10*24+1
         res = obj.clim_filter(xr_array_long_with_var, 24, 0.05, 10*24+1, sampling="1H", time_dim=time_dim, var_dim=var_dim)
-        assert len(res) == 4
+        assert len(res) == 5
 
         # check filter data properties
         assert res[0].shape == (*xr_array_long_with_var.shape, filter_order + 1)
@@ -349,7 +349,7 @@ class TestClimateFIRFilter:
                               var_dim=var_dim, new_dim="total_new_dim", window=("kaiser", 5), minimum_length=1000,
                               apriori=apriori, plot_dates=plot_dates)
 
-        assert res[0].shape == (*xr_array_long_with_var.shape, 1000 + 1)
+        assert res[0].shape == (*xr_array_long_with_var.shape, 1000 + 2)
         assert res[0].dims == (*xr_array_long_with_var.dims, "total_new_dim")
         assert np.testing.assert_almost_equal(
             res[1], obj._calculate_filter_coefficients(("kaiser", 5),  filter_order, 0.05, 24)) is None
diff --git a/test/test_helpers/test_testing_helpers.py b/test/test_helpers/test_testing_helpers.py
index bceed646c345d3add4602e67b55da1553eabdbaa..9b888a91a7c88a31764bd272632b1aab8e6e170f 100644
--- a/test/test_helpers/test_testing_helpers.py
+++ b/test/test_helpers/test_testing_helpers.py
@@ -1,4 +1,4 @@
-from mlair.helpers.testing import PyTestRegex, PyTestAllEqual, test_nested_equality
+from mlair.helpers.testing import PyTestRegex, PyTestAllEqual, check_nested_equality
 
 import re
 import xarray as xr
@@ -52,30 +52,30 @@ class TestPyTestAllEqual:
 class TestNestedEquality:
 
     def test_nested_equality_single_entries(self):
-        assert test_nested_equality(3, 3) is True
-        assert test_nested_equality(3.9, 3.9) is True
-        assert test_nested_equality(3.91, 3.9) is False
-        assert test_nested_equality("3", 3) is False
-        assert test_nested_equality("3", "3") is True
-        assert test_nested_equality(None, None) is True
+        assert check_nested_equality(3, 3) is True
+        assert check_nested_equality(3.9, 3.9) is True
+        assert check_nested_equality(3.91, 3.9) is False
+        assert check_nested_equality("3", 3) is False
+        assert check_nested_equality("3", "3") is True
+        assert check_nested_equality(None, None) is True
 
     def test_nested_equality_xarray(self):
         obj1 = xr.DataArray(np.random.randn(2, 3), dims=('x', 'y'), coords={'x': [10, 20], 'y': [0, 10, 20]})
         obj2 = xr.ones_like(obj1) * obj1
-        assert test_nested_equality(obj1, obj2) is True
+        assert check_nested_equality(obj1, obj2) is True
 
     def test_nested_equality_numpy(self):
         obj1 = np.random.randn(2, 3)
         obj2 = obj1 * 1
-        assert test_nested_equality(obj1, obj2) is True
+        assert check_nested_equality(obj1, obj2) is True
 
     def test_nested_equality_list_tuple(self):
-        assert test_nested_equality([3, 3], [3, 3]) is True
-        assert test_nested_equality((2, 6), (2, 6)) is True
-        assert test_nested_equality([3, 3.5], [3.5, 3]) is False
-        assert test_nested_equality([3, 3.5, 10], [3, 3.5]) is False
+        assert check_nested_equality([3, 3], [3, 3]) is True
+        assert check_nested_equality((2, 6), (2, 6)) is True
+        assert check_nested_equality([3, 3.5], [3.5, 3]) is False
+        assert check_nested_equality([3, 3.5, 10], [3, 3.5]) is False
 
     def test_nested_equality_dict(self):
-        assert test_nested_equality({"a": 3, "b": 10}, {"b": 10, "a": 3}) is True
-        assert test_nested_equality({"a": 3, "b": [10, 100]}, {"b": [10, 100], "a": 3}) is True
-        assert test_nested_equality({"a": 3, "b": 10, "c": "c"}, {"b": 10, "a": 3}) is False
+        assert check_nested_equality({"a": 3, "b": 10}, {"b": 10, "a": 3}) is True
+        assert check_nested_equality({"a": 3, "b": [10, 100]}, {"b": [10, 100], "a": 3}) is True
+        assert check_nested_equality({"a": 3, "b": 10, "c": "c"}, {"b": 10, "a": 3}) is False