diff --git a/pysteps/tests/test_spatialscores.py b/pysteps/tests/test_spatialscores.py
index 2debbe1fb..4c7307491 100644
--- a/pysteps/tests/test_spatialscores.py
+++ b/pysteps/tests/test_spatialscores.py
@@ -6,24 +6,20 @@
 from pysteps.tests.helpers import get_precipitation_fields
 from pysteps.verification import spatialscores
 
-try:
-    import pywt
-
-    PYWT_IMPORTED = True
-except ImportError:
-    PYWT_IMPORTED = False
-
 R = get_precipitation_fields(num_prev_files=1, return_raw=True)
-test_data = [(R[0], R[1], "FSS", [1], [10], None, 0.85161531)]
-if PYWT_IMPORTED:
-    test_data.append((R[0], R[1], "BMSE", [1], None, "Haar", 0.99989651))
-
+test_data = [
+    (R[0], R[1], "FSS", [1], [10], None, 0.85161531),
+    (R[0], R[1], "BMSE", [1], None, "Haar", 0.99989651),
+]
 
 @pytest.mark.parametrize(
     "X_f, X_o, name, thrs, scales, wavelet, expected", test_data
 )
 def test_intensity_scale(X_f, X_o, name, thrs, scales, wavelet, expected):
     """Test the intensity_scale."""
+    if name == "BMSE":
+        pytest.importorskip("pywt")
+
     assert_array_almost_equal(
         spatialscores.intensity_scale(X_f, X_o, name, thrs, scales, wavelet)[
             0
@@ -33,18 +29,26 @@ def test_intensity_scale(X_f, X_o, name, thrs, scales, wavelet, expected):
 
 
 R = get_precipitation_fields(num_prev_files=3, return_raw=True)
-test_data = [(R[:2], R[2:], "FSS", [1], [10], None, 0.85062658)]
-if PYWT_IMPORTED:
-    test_data.append((R[:2], R[2:], "BMSE", [1], None, "Haar", 0.99985691))
-
+test_data = [
+    (R[:2], R[2:], "FSS", [1], [10], None),
+    (R[:2], R[2:], "BMSE", [1], None, "Haar"),
+]
 
 @pytest.mark.parametrize(
-    "R1, R2, name, thrs, scales, wavelet, expected", test_data
+    "R1, R2, name, thrs, scales, wavelet", test_data
 )
 def test_intensity_scale_methods(
-    R1, R2, name, thrs, scales, wavelet, expected
+    R1, R2, name, thrs, scales, wavelet
 ):
     """Test the intensity_scale merge."""
+    if name == "BMSE":
+        pytest.importorskip("pywt")
+
+    # expected reult
+    int = spatialscores.intensity_scale_init(name, thrs, scales, wavelet)
+    spatialscores.intensity_scale_accum(int, R1[0], R1[1])
+    spatialscores.intensity_scale_accum(int, R2[0], R2[1])
+    expected = spatialscores.intensity_scale_compute(int)[0][0]
 
     # init
     int_1 = spatialscores.intensity_scale_init(name, thrs, scales, wavelet)