Add test for non-ascii variable names extraction.

Author: dukebody

tests/test_dataframe_mapper.py

@@ -1,3 +1,5 @@
+# -*- coding: utf8 -*-
+
 import pytest
 from pkg_resources import parse_version
 
@@ -128,6 +130,14 @@ def test_transformed_names_binarizer(complex_dataframe):
     assert mapper.transformed_names_ == ['target_a', 'target_b', 'target_c']
 
 
+def test_transformed_names_binarizer_unicode():
+    df = pd.DataFrame({'target': [u'ñ', u'á', u'é']})
+    mapper = DataFrameMapper([('target', LabelBinarizer())])
+    mapper.fit_transform(df)
+    expected_names = {u'target_ñ', u'target_á', u'target_é'}
+    assert set(mapper.transformed_names_) == expected_names
+
+
 def test_transformed_names_transformers_list(complex_dataframe):
     """
     When using a list of transformers, use them in inverse order to get the