Issue 8351. Suppress large diffs in unittest.TestCase.assertSequenceEqual.
diff --git a/Lib/unittest/case.py b/Lib/unittest/case.py
index 5c434d9..7608e30 100644
--- a/Lib/unittest/case.py
+++ b/Lib/unittest/case.py
@@ -13,7 +13,7 @@
)
__unittest = True
-
+TRUNCATED_DIFF = '\n[diff truncated...]'
class SkipTest(Exception):
"""
@@ -589,7 +589,8 @@
failUnlessRaises = _deprecate(assertRaises)
failIf = _deprecate(assertFalse)
- def assertSequenceEqual(self, seq1, seq2, msg=None, seq_type=None):
+ def assertSequenceEqual(self, seq1, seq2, msg=None, seq_type=None,
+ max_diff=80*8):
"""An equality assertion for ordered sequences (like lists and tuples).
For the purposes of this function, a valid ordered sequence type is one
@@ -602,6 +603,7 @@
datatype should be enforced.
msg: Optional message to use on failure instead of a list of
differences.
+ max_diff: Maximum size off the diff, larger diffs are not shown
"""
if seq_type is not None:
seq_type_name = seq_type.__name__
@@ -684,9 +686,14 @@
except (TypeError, IndexError, NotImplementedError):
differing += ('Unable to index element %d '
'of second %s\n' % (len1, seq_type_name))
- standardMsg = differing + '\n' + '\n'.join(
+ standardMsg = differing
+ diffMsg = '\n' + '\n'.join(
difflib.ndiff(pprint.pformat(seq1).splitlines(),
pprint.pformat(seq2).splitlines()))
+ if max_diff is None or len(diffMsg) <= max_diff:
+ standardMsg += diffMsg
+ else:
+ standardMsg += diffMsg[:max_diff] + TRUNCATED_DIFF
msg = self._formatMessage(msg, standardMsg)
self.fail(msg)