diff -r a5dc5867d5e8 Lib/test/test_traceback.py --- a/Lib/test/test_traceback.py Sat Mar 21 02:03:40 2015 -0700 +++ b/Lib/test/test_traceback.py Sat Mar 21 15:41:28 2015 +0200 @@ -6,6 +6,7 @@ import linecache import sys import unittest import re +from test import support from test.support import run_unittest, Error, captured_output from test.support import TESTFN, unlink, cpython_only from test.script_helper import assert_python_ok @@ -454,6 +455,126 @@ class CExcReportingTests(BaseExceptionRe return s.getvalue() +class LimitTests(unittest.TestCase): + + ''' Tests for limit argument. + It's enough to test extact_tb, extract_stack and format_exception ''' + + def last_raises1(self): + raise Exception('Last raised') + + def last_raises2(self): + self.last_raises1() + + def last_raises3(self): + self.last_raises2() + + def last_raises4(self): + self.last_raises3() + + def last_raises5(self): + self.last_raises4() + + def last_returns_frame1(self): + return sys._getframe() + + def last_returns_frame2(self): + return self.last_returns_frame1() + + def last_returns_frame3(self): + return self.last_returns_frame2() + + def last_returns_frame4(self): + return self.last_returns_frame3() + + def last_returns_frame5(self): + return self.last_returns_frame4() + + def test_extract_stack(self): + frame = self.last_returns_frame5() + def extract(**kwargs): + return traceback.extract_stack(frame, **kwargs) + def assertEqualExcept(actual, expected, ignore): + self.assertEqual(actual[:ignore], expected[:ignore]) + self.assertEqual(actual[ignore+1:], expected[ignore+1:]) + self.assertEqual(len(actual), len(expected)) + + with support.swap_attr(sys, 'tracebacklimit', 1000): + nolim = extract() + self.assertGreater(len(nolim), 5) + self.assertEqual(extract(limit=2), nolim[-2:]) + assertEqualExcept(extract(limit=100), nolim[-100:], -5-1) + self.assertEqual(extract(limit=-2), nolim[:2]) + assertEqualExcept(extract(limit=-100), nolim[:100], len(nolim)-5-1) + self.assertEqual(extract(limit=0), []) + del sys.tracebacklimit + assertEqualExcept(extract(), nolim, -5-1) + sys.tracebacklimit = 2 + self.assertEqual(extract(), nolim[-2:]) + self.assertEqual(extract(limit=3), nolim[-3:]) + self.assertEqual(extract(limit=-3), nolim[:3]) + sys.tracebacklimit = 0 + self.assertEqual(extract(), []) + sys.tracebacklimit = -1 + self.assertEqual(extract(), []) + + def test_extract_tb(self): + try: + self.last_raises5() + except Exception: + exc_type, exc_value, tb = sys.exc_info() + def extract(**kwargs): + return traceback.extract_tb(tb, **kwargs) + + with support.swap_attr(sys, 'tracebacklimit', 1000): + nolim = extract() + self.assertEqual(len(nolim), 5+1) + self.assertEqual(extract(limit=2), nolim[:2]) + self.assertEqual(extract(limit=10), nolim) + self.assertEqual(extract(limit=-2), nolim[-2:]) + self.assertEqual(extract(limit=-10), nolim) + self.assertEqual(extract(limit=0), []) + del sys.tracebacklimit + self.assertEqual(extract(), nolim) + sys.tracebacklimit = 2 + self.assertEqual(extract(), nolim[:2]) + self.assertEqual(extract(limit=3), nolim[:3]) + self.assertEqual(extract(limit=-3), nolim[-3:]) + sys.tracebacklimit = 0 + self.assertEqual(extract(), []) + sys.tracebacklimit = -1 + self.assertEqual(extract(), []) + + def test_format_exception(self): + try: + self.last_raises5() + except Exception: + exc_type, exc_value, tb = sys.exc_info() + # [1:-1] to exclude "Traceback (...)" header and + # exception type and value + def extract(**kwargs): + return traceback.format_exception(exc_type, exc_value, tb, **kwargs)[1:-1] + + with support.swap_attr(sys, 'tracebacklimit', 1000): + nolim = extract() + self.assertEqual(len(nolim), 5+1) + self.assertEqual(extract(limit=2), nolim[:2]) + self.assertEqual(extract(limit=10), nolim) + self.assertEqual(extract(limit=-2), nolim[-2:]) + self.assertEqual(extract(limit=-10), nolim) + self.assertEqual(extract(limit=0), []) + del sys.tracebacklimit + self.assertEqual(extract(), nolim) + sys.tracebacklimit = 2 + self.assertEqual(extract(), nolim[:2]) + self.assertEqual(extract(limit=3), nolim[:3]) + self.assertEqual(extract(limit=-3), nolim[-3:]) + sys.tracebacklimit = 0 + self.assertEqual(extract(), []) + sys.tracebacklimit = -1 + self.assertEqual(extract(), []) + + class MiscTracebackCases(unittest.TestCase): # # Check non-printing functions in traceback module @@ -593,17 +714,15 @@ class TestStack(unittest.TestCase): traceback.walk_stack(None), capture_locals=True, limit=1) s = some_inner(3, 4) self.assertEqual( - [' File "' + __file__ + '", line 593, ' - 'in some_inner\n' + [' File "%s", line %d, in some_inner\n' ' traceback.walk_stack(None), capture_locals=True, limit=1)\n' ' a = 1\n' ' b = 2\n' ' k = 3\n' - ' v = 4\n' + ' v = 4\n' % (__file__, some_inner.__code__.co_firstlineno + 4) ], s.format()) - class TestTracebackException(unittest.TestCase): def test_smoke(self): diff -r a5dc5867d5e8 Lib/traceback.py --- a/Lib/traceback.py Sat Mar 21 02:03:40 2015 -0700 +++ b/Lib/traceback.py Sat Mar 21 15:41:28 2015 +0200 @@ -1,8 +1,9 @@ """Extract, format and print information about Python stack traces.""" +import collections +import itertools import linecache import sys -import operator __all__ = ['extract_stack', 'extract_tb', 'format_exception', 'format_exception_only', 'format_list', 'format_stack', @@ -314,12 +315,17 @@ class StackSummary(list): """ if limit is None: limit = getattr(sys, 'tracebacklimit', None) + if limit is not None and limit < 0: + limit = 0 + if limit is not None: + if limit >= 0: + frame_gen = itertools.islice(frame_gen, limit) + else: + frame_gen = collections.deque(frame_gen, maxlen=-limit) result = klass() fnames = set() - for pos, (f, lineno) in enumerate(frame_gen): - if limit is not None and pos >= limit: - break + for f, lineno in frame_gen: co = f.f_code filename = co.co_filename name = co.co_name