Close issue #6210: Implement PEP 409
diff --git a/Lib/test/test_exceptions.py b/Lib/test/test_exceptions.py
index a7683ac..91d85ef 100644
--- a/Lib/test/test_exceptions.py
+++ b/Lib/test/test_exceptions.py
@@ -387,19 +387,36 @@
def testChainingAttrs(self):
e = Exception()
- self.assertEqual(e.__context__, None)
- self.assertEqual(e.__cause__, None)
+ self.assertIsNone(e.__context__)
+ self.assertIs(e.__cause__, Ellipsis)
e = TypeError()
- self.assertEqual(e.__context__, None)
- self.assertEqual(e.__cause__, None)
+ self.assertIsNone(e.__context__)
+ self.assertIs(e.__cause__, Ellipsis)
class MyException(EnvironmentError):
pass
e = MyException()
- self.assertEqual(e.__context__, None)
- self.assertEqual(e.__cause__, None)
+ self.assertIsNone(e.__context__)
+ self.assertIs(e.__cause__, Ellipsis)
+
+ def testChainingDescriptors(self):
+ try:
+ raise Exception()
+ except Exception as exc:
+ e = exc
+
+ self.assertIsNone(e.__context__)
+ self.assertIs(e.__cause__, Ellipsis)
+
+ e.__context__ = NameError()
+ e.__cause__ = None
+ self.assertIsInstance(e.__context__, NameError)
+ self.assertIsNone(e.__cause__)
+
+ e.__cause__ = Ellipsis
+ self.assertIs(e.__cause__, Ellipsis)
def testKeywordArgs(self):
# test that builtin exception don't take keyword args,
diff --git a/Lib/test/test_raise.py b/Lib/test/test_raise.py
index 92c50c7..8ae9210 100644
--- a/Lib/test/test_raise.py
+++ b/Lib/test/test_raise.py
@@ -3,12 +3,27 @@
"""Tests for the raise statement."""
-from test import support
+from test import support, script_helper
+import re
import sys
import types
import unittest
+try:
+ from resource import setrlimit, RLIMIT_CORE, error as resource_error
+except ImportError:
+ prepare_subprocess = None
+else:
+ def prepare_subprocess():
+ # don't create core file
+ try:
+ setrlimit(RLIMIT_CORE, (0, 0))
+ except (ValueError, resource_error):
+ pass
+
+
+
def get_tb():
try:
raise OSError()
@@ -77,6 +92,16 @@
nested_reraise()
self.assertRaises(TypeError, reraise)
+ def test_raise_from_None(self):
+ try:
+ try:
+ raise TypeError("foo")
+ except:
+ raise ValueError() from None
+ except ValueError as e:
+ self.assertTrue(isinstance(e.__context__, TypeError))
+ self.assertIsNone(e.__cause__)
+
def test_with_reraise1(self):
def reraise():
try:
@@ -139,6 +164,23 @@
class TestCause(unittest.TestCase):
+
+ def testCauseSyntax(self):
+ try:
+ try:
+ try:
+ raise TypeError
+ except Exception:
+ raise ValueError from None
+ except ValueError as exc:
+ self.assertIsNone(exc.__cause__)
+ raise exc from Ellipsis
+ except ValueError as exc:
+ e = exc
+
+ self.assertIs(e.__cause__, Ellipsis)
+ self.assertIsInstance(e.__context__, TypeError)
+
def test_invalid_cause(self):
try:
raise IndexError from 5
@@ -178,6 +220,44 @@
class TestTraceback(unittest.TestCase):
+
+ def get_output(self, code, filename=None):
+ """
+ Run the specified code in Python (in a new child process) and read the
+ output from the standard error or from a file (if filename is set).
+ Return the output lines as a list.
+ """
+ options = {}
+ if prepare_subprocess:
+ options['preexec_fn'] = prepare_subprocess
+ process = script_helper.spawn_python('-c', code, **options)
+ stdout, stderr = process.communicate()
+ exitcode = process.wait()
+ output = support.strip_python_stderr(stdout)
+ output = output.decode('ascii', 'backslashreplace')
+ if filename:
+ self.assertEqual(output, '')
+ with open(filename, "rb") as fp:
+ output = fp.read()
+ output = output.decode('ascii', 'backslashreplace')
+ output = re.sub('Current thread 0x[0-9a-f]+',
+ 'Current thread XXX',
+ output)
+ return output.splitlines(), exitcode
+
+ def test_traceback_verbiage(self):
+ code = """
+try:
+ raise ValueError
+except:
+ raise NameError from None
+"""
+ text, exitcode = self.get_output(code)
+ self.assertEqual(len(text), 3)
+ self.assertTrue(text[0].startswith('Traceback'))
+ self.assertTrue(text[1].startswith(' File '))
+ self.assertTrue(text[2].startswith('NameError'))
+
def test_sets_traceback(self):
try:
raise IndexError()
diff --git a/Lib/test/test_traceback.py b/Lib/test/test_traceback.py
index 4752d37..5bce2af 100644
--- a/Lib/test/test_traceback.py
+++ b/Lib/test/test_traceback.py
@@ -246,6 +246,21 @@
self.check_zero_div(blocks[0])
self.assertIn('inner_raise() # Marker', blocks[2])
+ def test_context_suppression(self):
+ try:
+ try:
+ raise Exception
+ except:
+ raise ZeroDivisionError from None
+ except ZeroDivisionError as _:
+ e = _
+ lines = self.get_report(e).splitlines()
+ self.assertEqual(len(lines), 4)
+ self.assertTrue(lines[0].startswith('Traceback'))
+ self.assertTrue(lines[1].startswith(' File'))
+ self.assertIn('ZeroDivisionError from None', lines[2])
+ self.assertTrue(lines[3].startswith('ZeroDivisionError'))
+
def test_cause_and_context(self):
# When both a cause and a context are set, only the cause should be
# displayed and the context should be muted.