TST: Add tests for filter method

Author: Licht-T

pandas/tests/frame/test_axis_select_reindex.py

@@ -884,6 +884,22 @@ def test_filter_regex_search(self):
         exp = df[[x for x in df.columns if 'BB' in x]]
         assert_frame_equal(result, exp)
 
+    @pytest.mark.parametrize('exp', ['a', u'a'])
+    def test_filter_unicode(self, exp):
+        df = DataFrame({u'a': [1, 2], u'b': [3, 4]})
+        expected = DataFrame({u'a': [1, 2]})
+
+        assert_frame_equal(df.filter(like=exp), expected)
+        assert_frame_equal(df.filter(regex=exp), expected)
+
+    @pytest.mark.parametrize('exp', ['a', u'a'])
+    def test_filter_bytestring(self, exp):
+        df = DataFrame({b'a': [1, 2], b'b': [3, 4]})
+        expected = DataFrame({b'a': [1, 2]})
+
+        assert_frame_equal(df.filter(like=exp), expected)
+        assert_frame_equal(df.filter(regex=exp), expected)
+
     def test_filter_corner(self):
         empty = DataFrame()