diff --git a/test/test_helpers/test_tables.py b/test/test_helpers/test_tables.py
new file mode 100644
index 0000000000000000000000000000000000000000..1b19b19bac65a9c44b7a46d8ec0b4bff33598a55
--- /dev/null
+++ b/test/test_helpers/test_tables.py
@@ -0,0 +1,21 @@
+import pandas as pd
+import numpy as np
+
+from mlair.helpers import tables
+
+
+class TestTables:
+
+    def test_create_column_format_for_tex(self):
+        df = pd.DataFrame(np.ones((2, 1)))
+        df_col = tables.create_column_format_for_tex(df)  # len: 1+1
+        assert df_col == 'lr'
+        assert len(df_col) == 2
+        df = pd.DataFrame(np.ones((2, 2)))
+        df_col = tables.create_column_format_for_tex(df)  # len: 2+1
+        assert df_col == 'lcr'
+        assert len(df_col) == 3
+        df = pd.DataFrame(np.ones((2, 3)))
+        df_col = tables.create_column_format_for_tex(df)  # len: 3+1
+        assert df_col == 'lccr'
+        assert len(df_col) == 4
diff --git a/test/test_run_modules/test_pre_processing.py b/test/test_run_modules/test_pre_processing.py
index b5a1914e6b2aacd238f244d304184d9754326db7..5ae64bf3d535e72d9361394741ed8b8094091b1d 100644
--- a/test/test_run_modules/test_pre_processing.py
+++ b/test/test_run_modules/test_pre_processing.py
@@ -140,40 +140,28 @@ class TestPreProcessing:
         data_preparation = AbstractDataHandler
         stations = ['DEBW107', 'DEBY081']
         assert pre.transformation(data_preparation, stations) is None
+
         class data_preparation_no_trans: pass
+
         assert pre.transformation(data_preparation_no_trans, stations) is None
 
-    @pytest.fixture
-    def dummy_df(self):
-        data_dict = {'station_name': {'DEBW013': 'Stuttgart Bad Cannstatt', 'DEBW076': 'Baden-Baden',
-                                      'DEBW087': 'Schwäbische_Alb', 'DEBW107': 'Tübingen',
-                                      'DEBY081': 'Garmisch-Partenkirchen/Kreuzeckbahnstraße', '# Stations': np.nan,
-                                      '# Samples': np.nan},
-                     'station_lon': {'DEBW013': 9.2297, 'DEBW076': 8.2202, 'DEBW087': 9.2076, 'DEBW107': 9.0512,
-                                     'DEBY081': 11.0631, '# Stations': np.nan, '# Samples': np.nan},
-                     'station_lat': {'DEBW013': 48.8088, 'DEBW076': 48.7731, 'DEBW087': 48.3458, 'DEBW107': 48.5077,
-                                     'DEBY081': 47.4764, '# Stations': np.nan, '# Samples': np.nan},
-                     'station_alt': {'DEBW013': 235.0, 'DEBW076': 148.0, 'DEBW087': 798.0, 'DEBW107': 325.0,
-                                     'DEBY081': 735.0, '# Stations': np.nan, '# Samples': np.nan},
-                     'train': {'DEBW013': 1413, 'DEBW076': 3002, 'DEBW087': 3016, 'DEBW107': 1782, 'DEBY081': 2837,
-                               '# Stations': 6, '# Samples': 12050},
-                     'val': {'DEBW013': 698, 'DEBW076': 715, 'DEBW087': 700, 'DEBW107': 701, 'DEBY081': 456,
-                             '# Stations': 6, '# Samples': 3270},
-                     'test': {'DEBW013': 1066, 'DEBW076': 696, 'DEBW087': 1080, 'DEBW107': 1080, 'DEBY081': 700,
-                              '# Stations': 6, '# Samples': 4622}}
-        df = pd.DataFrame.from_dict(data_dict)
-        return df
-
-    def test_create_column_format_for_tex(self):
-        df = pd.DataFrame(np.ones((2, 1)))
-        df_col = PreProcessing.create_column_format_for_tex(df)  # len: 1+1
-        assert df_col == 'lr'
-        assert len(df_col) == 2
-        df = pd.DataFrame(np.ones((2, 2)))
-        df_col = PreProcessing.create_column_format_for_tex(df)  # len: 2+1
-        assert df_col == 'lcr'
-        assert len(df_col) == 3
-        df = pd.DataFrame(np.ones((2, 3)))
-        df_col = PreProcessing.create_column_format_for_tex(df) # len: 3+1
-        assert df_col == 'lccr'
-        assert len(df_col) == 4
+    # @pytest.fixture
+    # def dummy_df(self):
+    #     data_dict = {'station_name': {'DEBW013': 'Stuttgart Bad Cannstatt', 'DEBW076': 'Baden-Baden',
+    #                                   'DEBW087': 'Schwäbische_Alb', 'DEBW107': 'Tübingen',
+    #                                   'DEBY081': 'Garmisch-Partenkirchen/Kreuzeckbahnstraße', '# Stations': np.nan,
+    #                                   '# Samples': np.nan},
+    #                  'station_lon': {'DEBW013': 9.2297, 'DEBW076': 8.2202, 'DEBW087': 9.2076, 'DEBW107': 9.0512,
+    #                                  'DEBY081': 11.0631, '# Stations': np.nan, '# Samples': np.nan},
+    #                  'station_lat': {'DEBW013': 48.8088, 'DEBW076': 48.7731, 'DEBW087': 48.3458, 'DEBW107': 48.5077,
+    #                                  'DEBY081': 47.4764, '# Stations': np.nan, '# Samples': np.nan},
+    #                  'station_alt': {'DEBW013': 235.0, 'DEBW076': 148.0, 'DEBW087': 798.0, 'DEBW107': 325.0,
+    #                                  'DEBY081': 735.0, '# Stations': np.nan, '# Samples': np.nan},
+    #                  'train': {'DEBW013': 1413, 'DEBW076': 3002, 'DEBW087': 3016, 'DEBW107': 1782, 'DEBY081': 2837,
+    #                            '# Stations': 6, '# Samples': 12050},
+    #                  'val': {'DEBW013': 698, 'DEBW076': 715, 'DEBW087': 700, 'DEBW107': 701, 'DEBY081': 456,
+    #                          '# Stations': 6, '# Samples': 3270},
+    #                  'test': {'DEBW013': 1066, 'DEBW076': 696, 'DEBW087': 1080, 'DEBW107': 1080, 'DEBY081': 700,
+    #                           '# Stations': 6, '# Samples': 4622}}
+    #     df = pd.DataFrame.from_dict(data_dict)
+    #     return df