[Python-checkins] bpo-24959: fix unittest.assertRaises bug where traceback entries are dropped from chained exceptions (GH-23688)
iritkatriel
webhook-mailer at python.org
Tue Mar 8 16:44:04 EST 2022
https://github.com/python/cpython/commit/88b7d86a73da9388aa65c96401c2984c8c16f8db
commit: 88b7d86a73da9388aa65c96401c2984c8c16f8db
branch: main
author: Irit Katriel <1055913+iritkatriel at users.noreply.github.com>
committer: iritkatriel <1055913+iritkatriel at users.noreply.github.com>
date: 2022-03-08T21:43:49Z
summary:
bpo-24959: fix unittest.assertRaises bug where traceback entries are dropped from chained exceptions (GH-23688)
files:
A Misc/NEWS.d/next/Library/2021-09-06-15-46-53.bpo-24959.UVFgiO.rst
M Lib/unittest/result.py
M Lib/unittest/test/test_result.py
diff --git a/Lib/unittest/result.py b/Lib/unittest/result.py
index ce7468e31481f..3da7005e603f4 100644
--- a/Lib/unittest/result.py
+++ b/Lib/unittest/result.py
@@ -173,18 +173,10 @@ def stop(self):
def _exc_info_to_string(self, err, test):
"""Converts a sys.exc_info()-style tuple of values into a string."""
exctype, value, tb = err
- # Skip test runner traceback levels
- while tb and self._is_relevant_tb_level(tb):
- tb = tb.tb_next
-
- if exctype is test.failureException:
- # Skip assert*() traceback levels
- length = self._count_relevant_tb_levels(tb)
- else:
- length = None
+ tb = self._clean_tracebacks(exctype, value, tb, test)
tb_e = traceback.TracebackException(
exctype, value, tb,
- limit=length, capture_locals=self.tb_locals, compact=True)
+ capture_locals=self.tb_locals, compact=True)
msgLines = list(tb_e.format())
if self.buffer:
@@ -200,16 +192,49 @@ def _exc_info_to_string(self, err, test):
msgLines.append(STDERR_LINE % error)
return ''.join(msgLines)
+ def _clean_tracebacks(self, exctype, value, tb, test):
+ ret = None
+ first = True
+ excs = [(exctype, value, tb)]
+ while excs:
+ (exctype, value, tb) = excs.pop()
+ # Skip test runner traceback levels
+ while tb and self._is_relevant_tb_level(tb):
+ tb = tb.tb_next
+
+ # Skip assert*() traceback levels
+ if exctype is test.failureException:
+ self._remove_unittest_tb_frames(tb)
+
+ if first:
+ ret = tb
+ first = False
+ else:
+ value.__traceback__ = tb
+
+ if value is not None:
+ for c in (value.__cause__, value.__context__):
+ if c is not None:
+ excs.append((type(c), c, c.__traceback__))
+ return ret
def _is_relevant_tb_level(self, tb):
return '__unittest' in tb.tb_frame.f_globals
- def _count_relevant_tb_levels(self, tb):
- length = 0
+ def _remove_unittest_tb_frames(self, tb):
+ '''Truncates usercode tb at the first unittest frame.
+
+ If the first frame of the traceback is in user code,
+ the prefix up to the first unittest frame is returned.
+ If the first frame is already in the unittest module,
+ the traceback is not modified.
+ '''
+ prev = None
while tb and not self._is_relevant_tb_level(tb):
- length += 1
+ prev = tb
tb = tb.tb_next
- return length
+ if prev is not None:
+ prev.tb_next = None
def __repr__(self):
return ("<%s run=%i errors=%i failures=%i>" %
diff --git a/Lib/unittest/test/test_result.py b/Lib/unittest/test/test_result.py
index 224a78463edc9..c616f28dfee92 100644
--- a/Lib/unittest/test/test_result.py
+++ b/Lib/unittest/test/test_result.py
@@ -220,6 +220,61 @@ def test_1(self):
self.assertIs(test_case, test)
self.assertIsInstance(formatted_exc, str)
+ def test_addFailure_filter_traceback_frames(self):
+ class Foo(unittest.TestCase):
+ def test_1(self):
+ pass
+
+ test = Foo('test_1')
+ def get_exc_info():
+ try:
+ test.fail("foo")
+ except:
+ return sys.exc_info()
+
+ exc_info_tuple = get_exc_info()
+
+ full_exc = traceback.format_exception(*exc_info_tuple)
+
+ result = unittest.TestResult()
+ result.startTest(test)
+ result.addFailure(test, exc_info_tuple)
+ result.stopTest(test)
+
+ formatted_exc = result.failures[0][1]
+ dropped = [l for l in full_exc if l not in formatted_exc]
+ self.assertEqual(len(dropped), 1)
+ self.assertIn("raise self.failureException(msg)", dropped[0])
+
+ def test_addFailure_filter_traceback_frames_context(self):
+ class Foo(unittest.TestCase):
+ def test_1(self):
+ pass
+
+ test = Foo('test_1')
+ def get_exc_info():
+ try:
+ try:
+ test.fail("foo")
+ except:
+ raise ValueError(42)
+ except:
+ return sys.exc_info()
+
+ exc_info_tuple = get_exc_info()
+
+ full_exc = traceback.format_exception(*exc_info_tuple)
+
+ result = unittest.TestResult()
+ result.startTest(test)
+ result.addFailure(test, exc_info_tuple)
+ result.stopTest(test)
+
+ formatted_exc = result.failures[0][1]
+ dropped = [l for l in full_exc if l not in formatted_exc]
+ self.assertEqual(len(dropped), 1)
+ self.assertIn("raise self.failureException(msg)", dropped[0])
+
# "addError(test, err)"
# ...
# "Called when the test case test raises an unexpected exception err
diff --git a/Misc/NEWS.d/next/Library/2021-09-06-15-46-53.bpo-24959.UVFgiO.rst b/Misc/NEWS.d/next/Library/2021-09-06-15-46-53.bpo-24959.UVFgiO.rst
new file mode 100644
index 0000000000000..b702986f9468a
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2021-09-06-15-46-53.bpo-24959.UVFgiO.rst
@@ -0,0 +1 @@
+Fix bug where :mod:`unittest` sometimes drops frames from tracebacks of exceptions raised in tests.
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