warnings.formatwarning(): catch exceptions

Issue #21925: warnings.formatwarning() now catches exceptions on
linecache.getline(...) to be able to log ResourceWarning emitted late during
the Python shutdown process.

1 files changed, 17 insertions, 0 deletions

diff --git a/Lib/test/test_warnings/__init__.py b/Lib/test/test_warnings/__init__.py
index eda755d..633b2ac 100644
--- a/Lib/test/test_warnings/__init__.py
+++ b/Lib/test/test_warnings/__init__.py
@@ -953,6 +953,23 @@ a=A()
         # of the script
         self.assertEqual(err, b'__main__:7: UserWarning: test')
 
+    def test_late_resource_warning(self):
+        # Issue #21925: Emitting a ResourceWarning late during the Python
+        # shutdown must be logged.
+
+        expected = b"sys:1: ResourceWarning: unclosed file "
+
+        # don't import the warnings module
+        # (_warnings will try to import it)
+        code = "f = open(%a)" % __file__
+        rc, out, err = assert_python_ok("-c", code)
+        self.assertTrue(err.startswith(expected), ascii(err))
+
+        # import the warnings module
+        code = "import warnings; f = open(%a)" % __file__
+        rc, out, err = assert_python_ok("-c", code)
+        self.assertTrue(err.startswith(expected), ascii(err))
+
 
 def setUpModule():
     py_warnings.onceregistry.clear()