Safely raise errors when object contains unicode

doc/source/whatsnew/v0.23.0.txt

@@ -1165,3 +1165,4 @@ Other
 
 - Improved error message when attempting to use a Python keyword as an identifier in a ``numexpr`` backed query (:issue:`18221`)
 - Bug in accessing a :func:`pandas.get_option`, which raised ``KeyError`` rather than ``OptionError`` when looking up a non-existant option key in some cases (:issue:`19789`)
+- Bug in :func:`raise_assert_detail` for Series and DataFrames with differing unicode data (:issue:`20503`)

pandas/tests/util/test_testing.py

@@ -276,6 +276,19 @@ def test_numpy_array_equal_message(self):
             assert_almost_equal(np.array([[1, 2], [3, 4]]),
                                 np.array([[1, 3], [3, 4]]))
 
+        expected = """numpy array are different
+
+numpy array values are different \\(33\\.33333 %\\)
+\\[left\\]:  \\[á, à, ä\\]
+\\[right\\]: \\[á, à, å\\]"""
+
+        with tm.assert_raises_regex(AssertionError, expected):
+            assert_numpy_array_equal(np.array([u"á", u"à", u"ä"]),
+                                     np.array([u"á", u"à", u"å"]))
+        with tm.assert_raises_regex(AssertionError, expected):
+            assert_almost_equal(np.array([u"á", u"à", u"ä"]),
+                                np.array([u"á", u"à", u"å"]))
+
         # allow to overwrite message
         expected = """Index are different
 
@@ -499,10 +512,12 @@ def _assert_not_equal(self, a, b, **kwargs):
     def test_equal(self):
         self._assert_equal(Series(range(3)), Series(range(3)))
         self._assert_equal(Series(list('abc')), Series(list('abc')))
+        self._assert_equal(Series(list(u'áàä')), Series(list(u'áàä')))
 
     def test_not_equal(self):
         self._assert_not_equal(Series(range(3)), Series(range(3)) + 1)
         self._assert_not_equal(Series(list('abc')), Series(list('xyz')))
+        self._assert_not_equal(Series(list(u'áàä')), Series(list(u'éèë')))
         self._assert_not_equal(Series(range(3)), Series(range(4)))
         self._assert_not_equal(
             Series(range(3)), Series(
@@ -678,6 +693,21 @@ def test_frame_equal_message(self):
                                pd.DataFrame({'A': [1, 2, 3], 'B': [4, 5, 7]}),
                                by_blocks=True)
 
+        expected = """DataFrame\\.iloc\\[:, 1\\] are different
+
+DataFrame\\.iloc\\[:, 1\\] values are different \\(33\\.33333 %\\)
+\\[left\\]:  \\[é, è, ë\\]
+\\[right\\]: \\[é, è, e̊\\]"""
+
+        with tm.assert_raises_regex(AssertionError, expected):
+            assert_frame_equal(pd.DataFrame({'A': [u"á", u"à", u"ä"], 'E': [u"é", u"è", u"ë"]}),
+                               pd.DataFrame({'A': [u"á", u"à", u"ä"], 'E': [u"é", u"è", u"e̊"]}))
+
+        with tm.assert_raises_regex(AssertionError, expected):
+            assert_frame_equal(pd.DataFrame({'A': [u"á", u"à", u"ä"], 'E': [u"é", u"è", u"ë"]}),
+                               pd.DataFrame({'A': [u"á", u"à", u"ä"], 'E': [u"é", u"è", u"e̊"]}),
+                               by_blocks=True)
+
 
 class TestAssertCategoricalEqual(object):
 

pandas/util/testing.py

@@ -31,7 +31,7 @@
     is_interval_dtype,
     is_sequence,
     is_list_like)
-from pandas.io.formats.printing import pprint_thing
+from pandas.io.formats.printing import pprint_thing_encoded
 from pandas.core.algorithms import take_1d
 import pandas.core.common as com
 
@@ -989,11 +989,11 @@ def assert_categorical_equal(left, right, check_dtype=True,
 
 def raise_assert_detail(obj, message, left, right, diff=None):
     if isinstance(left, np.ndarray):
-        left = pprint_thing(left)
+        left = pprint_thing_encoded(left, encoding=pd.options.display.encoding)
     elif is_categorical_dtype(left):
         left = repr(left)
     if isinstance(right, np.ndarray):
-        right = pprint_thing(right)
+        right = pprint_thing_encoded(right, encoding=pd.options.display.encoding)
     elif is_categorical_dtype(right):
         right = repr(right)