diff --git a/tests/helper.py b/tests/helper.py
index b91d623..2654a20 100644
--- a/tests/helper.py
+++ b/tests/helper.py
@@ -6,19 +6,23 @@
 
 def assertDataFramesEqual(self: unittest.TestCase, first: pandas.DataFrame, second: pandas.DataFrame) -> bool:
     for index, column in enumerate(first.columns):
-        self.assertEqual(first.dtypes.iloc[index], second.dtypes.iloc[index], "type mismatch between dataframes")
+        self.assertEqual(first.dtypes.iloc[index], second.dtypes.iloc[index], f"{column}: type mismatch between dataframes")
         
-        self.assertTrue((first[column].isna() == second[column].isna()).all(), "not all NaN are equal")
+        self.assertTrue((first[column].isna() == second[column].isna()).all(), f"{column}: not all NaN are equal")
 
         if (
             pandas.api.types.is_integer_dtype(first[column])
             or pandas.api.types.is_string_dtype(first[column])
             or pandas.api.types.is_bool_dtype(first[column])
         ):
-            self.assertTrue((first[~first[column].isna()][column] == second[~second[column].isna()][column]).all(), "not all non-NaN are equal in comparing int/string/bool")
+            self.assertTrue((first[~first[column].isna()][column] == second[~second[column].isna()][column]).all(), f"{column}: not all non-NaN are equal in comparing int/string/bool")
 
         elif pandas.api.types.is_float_dtype(first[column]):
-            self.assertTrue(numpy.allclose(first[~first[column].isna()][column], second[~second[column].isna()][column]), "not all non-NaN are equal in comparing float")
+            self.assertTrue(numpy.allclose(
+                first[~first[column].isna()][column],
+                second[~second[column].isna()][column],
+                equal_nan=True
+            ), f"{column}: not all non-NaN are equal in comparing float")
 
         else:
-            self.fail(f"Column {column} is of an unknown type: {first[column].dtype}")
+            self.fail(f"{column}: unknown type: {first[column].dtype}")