bpo-37526: Add support.catch_threading_exception() (GH-14664) (GH-14666)

Context manager catching threading.Thread exception using
threading.excepthook.
(cherry picked from commit 91b4f7ab7f9a5e0908b91379ee085ae087a76483)

Co-authored-by: Victor Stinner <vstinner@redhat.com>

1 files changed, 57 insertions, 0 deletions

diff --git a/Lib/test/support/__init__.py b/Lib/test/support/__init__.py
index 1c91fc4..a0fe086 100644
--- a/Lib/test/support/__init__.py
+++ b/Lib/test/support/__init__.py
@@ -3157,3 +3157,60 @@ class catch_unraisable_exception:
     def __exit__(self, *exc_info):
         sys.unraisablehook = self._old_hook
         del self.unraisable
+
+
+class catch_threading_exception:
+    """
+    Context manager catching threading.Thread exception using
+    threading.excepthook.
+
+    Attributes set when an exception is catched:
+
+    * exc_type
+    * exc_value
+    * exc_traceback
+    * thread
+
+    See threading.excepthook() documentation for these attributes.
+
+    These attributes are deleted at the context manager exit.
+
+    Usage:
+
+        with support.catch_threading_exception() as cm:
+            # code spawning a thread which raises an exception
+            ...
+
+            # check the thread exception, use cm attributes:
+            # exc_type, exc_value, exc_traceback, thread
+            ...
+
+        # exc_type, exc_value, exc_traceback, thread attributes of cm no longer
+        # exists at this point
+        # (to avoid reference cycles)
+    """
+
+    def __init__(self):
+        self.exc_type = None
+        self.exc_value = None
+        self.exc_traceback = None
+        self.thread = None
+        self._old_hook = None
+
+    def _hook(self, args):
+        self.exc_type = args.exc_type
+        self.exc_value = args.exc_value
+        self.exc_traceback = args.exc_traceback
+        self.thread = args.thread
+
+    def __enter__(self):
+        self._old_hook = threading.excepthook
+        threading.excepthook = self._hook
+        return self
+
+    def __exit__(self, *exc_info):
+        threading.excepthook = self._old_hook
+        del self.exc_type
+        del self.exc_value
+        del self.exc_traceback
+        del self.thread