Issue #18996: TestCase.assertEqual() now more cleverly shorten differing

strings in error report.

1 files changed, 7 insertions, 13 deletions

diff --git a/Lib/unittest/case.py b/Lib/unittest/case.py
index 2909610..7ed932f 100644
--- a/Lib/unittest/case.py
+++ b/Lib/unittest/case.py
@@ -12,7 +12,7 @@ import contextlib
 
 from . import result
 from .util import (strclass, safe_repr, _count_diff_all_purpose,
-                   _count_diff_hashable)
+                   _count_diff_hashable, _common_shorten_repr)
 
 __unittest = True
 
@@ -770,7 +770,7 @@ class TestCase(object):
     def _baseAssertEqual(self, first, second, msg=None):
         """The default assertEqual implementation, not type specific."""
         if not first == second:
-            standardMsg = '%s != %s' % (safe_repr(first), safe_repr(second))
+            standardMsg = '%s != %s' % _common_shorten_repr(first, second)
             msg = self._formatMessage(msg, standardMsg)
             raise self.failureException(msg)
 
@@ -905,14 +905,9 @@ class TestCase(object):
             if seq1 == seq2:
                 return
 
-            seq1_repr = safe_repr(seq1)
-            seq2_repr = safe_repr(seq2)
-            if len(seq1_repr) > 30:
-                seq1_repr = seq1_repr[:30] + '...'
-            if len(seq2_repr) > 30:
-                seq2_repr = seq2_repr[:30] + '...'
-            elements = (seq_type_name.capitalize(), seq1_repr, seq2_repr)
-            differing = '%ss differ: %s != %s\n' % elements
+            differing = '%ss differ: %s != %s\n' % (
+                    (seq_type_name.capitalize(),) +
+                    _common_shorten_repr(seq1, seq2))
 
             for i in range(min(len1, len2)):
                 try:
@@ -1070,7 +1065,7 @@ class TestCase(object):
         self.assertIsInstance(d2, dict, 'Second argument is not a dictionary')
 
         if d1 != d2:
-            standardMsg = '%s != %s' % (safe_repr(d1, True), safe_repr(d2, True))
+            standardMsg = '%s != %s' % _common_shorten_repr(d1, d2)
             diff = ('\n' + '\n'.join(difflib.ndiff(
                            pprint.pformat(d1).splitlines(),
                            pprint.pformat(d2).splitlines())))
@@ -1154,8 +1149,7 @@ class TestCase(object):
             if len(firstlines) == 1 and first.strip('\r\n') == first:
                 firstlines = [first + '\n']
                 secondlines = [second + '\n']
-            standardMsg = '%s != %s' % (safe_repr(first, True),
-                                        safe_repr(second, True))
+            standardMsg = '%s != %s' % _common_shorten_repr(first, second)
             diff = '\n' + ''.join(difflib.ndiff(firstlines, secondlines))
             standardMsg = self._truncateMessage(standardMsg, diff)
             self.fail(self._formatMessage(msg, standardMsg))