Do not show context if cause

Author: Carreau

Lib/pdb.py

@@ -423,7 +423,7 @@ def interaction(self, frame, tb_or_exc):
             tb_or_exc, exception = tb_or_exc.__traceback__, tb_or_exc
             self._chained_exceptions = [exception]
             current = exception
-            while current := current.__context__:
+            while current := (current.__cause__ or current.__context__):
                 self._chained_exception_index += 1
                 self._chained_exceptions.insert(0, current)
         else:

Lib/test/test_pdb.py

@@ -904,6 +904,129 @@ def test_post_mortem_chained():
     """
 
 
+def test_post_mortem_cause_no_context():
+    """Test post mortem traceback debugging of chained exception
+
+    >>> def main():
+    ...     try:
+    ...         raise ValueError('Context Not Shown')
+    ...     except Exception as e1:
+    ...         raise ValueError("With Cause") from TypeError('The Cause')
+
+    >>> def test_function():
+    ...     import pdb;
+    ...     instance = pdb.Pdb(nosigint=True, readrc=False)
+    ...     try:
+    ...         main()
+    ...     except Exception as e:
+    ...         # same as pdb.post_mortem(e), but with custom pdb instance.
+    ...         instance.reset()
+    ...         instance.interaction(None, e)
+
+    >>> with PdbTestInput([  # doctest: +ELLIPSIS, +NORMALIZE_WHITESPACE
+    ...     'exceptions',
+    ...     'exceptions 1',
+    ...     'up',
+    ...     'down',
+    ...     'exit',
+    ... ]):
+    ...    try:
+    ...        test_function()
+    ...    except ValueError:
+    ...        print('Ok.')
+    > <doctest test.test_pdb.test_post_mortem_cause_no_context[0]>(5)main()
+    -> raise ValueError("With Cause") from TypeError('The Cause')
+    (Pdb) exceptions
+      0 TypeError('The Cause')
+    > 1 ValueError('With Cause')
+    (Pdb) exceptions 1
+    > <doctest test.test_pdb.test_post_mortem_cause_no_context[0]>(5)main()
+    -> raise ValueError("With Cause") from TypeError('The Cause')
+    (Pdb) up
+    > <doctest test.test_pdb.test_post_mortem_cause_no_context[1]>(5)test_function()
+    -> main()
+    (Pdb) down
+    > <doctest test.test_pdb.test_post_mortem_cause_no_context[0]>(5)main()
+    -> raise ValueError("With Cause") from TypeError('The Cause')
+    (Pdb) exit"""
+
+
+def test_post_mortem_context_of_the_cause():
+    """Test post mortem traceback debugging of chained exception
+
+
+    >>> def main():
+    ...     try:
+    ...         raise TypeError('Context of the cause')
+    ...     except Exception as e1:
+    ...         try:
+    ...             raise ValueError('Root Cause')
+    ...         except Exception as e2:
+    ...             ex = e2
+    ...         raise ValueError("With Cause, and cause has context") from ex
+
+    >>> def test_function():
+    ...     import pdb;
+    ...     instance = pdb.Pdb(nosigint=True, readrc=False)
+    ...     try:
+    ...         main()
+    ...     except Exception as e:
+    ...         # same as pdb.post_mortem(e), but with custom pdb instance.
+    ...         instance.reset()
+    ...         instance.interaction(None, e)
+
+    >>> with PdbTestInput([  # doctest: +ELLIPSIS, +NORMALIZE_WHITESPACE
+    ...     'exceptions',
+    ...     'exceptions 2',
+    ...     'up',
+    ...     'down',
+    ...     'exceptions 3',
+    ...     'up',
+    ...     'down',
+    ...     'exceptions 4',
+    ...     'up',
+    ...     'down',
+    ...     'exit',
+    ... ]):
+    ...    try:
+    ...        test_function()
+    ...    except ValueError:
+    ...        print('Correctly reraised.')
+    > <doctest test.test_pdb.test_post_mortem_context_of_the_cause[0]>(9)main()
+    -> raise ValueError("With Cause, and cause has context") from ex
+    (Pdb) exceptions
+      0 TypeError('Context of the cause')
+      1 ValueError('Root Cause')
+    > 2 ValueError('With Cause, and cause has context')
+    (Pdb) exceptions 2
+    > <doctest test.test_pdb.test_post_mortem_context_of_the_cause[0]>(9)main()
+    -> raise ValueError("With Cause, and cause has context") from ex
+    (Pdb) up
+    > <doctest test.test_pdb.test_post_mortem_context_of_the_cause[1]>(5)test_function()
+    -> main()
+    (Pdb) down
+    > <doctest test.test_pdb.test_post_mortem_context_of_the_cause[0]>(9)main()
+    -> raise ValueError("With Cause, and cause has context") from ex
+    (Pdb) exceptions 3
+    *** No exception with that number
+    (Pdb) up
+    > <doctest test.test_pdb.test_post_mortem_context_of_the_cause[1]>(5)test_function()
+    -> main()
+    (Pdb) down
+    > <doctest test.test_pdb.test_post_mortem_context_of_the_cause[0]>(9)main()
+    -> raise ValueError("With Cause, and cause has context") from ex
+    (Pdb) exceptions 4
+    *** No exception with that number
+    (Pdb) up
+    > <doctest test.test_pdb.test_post_mortem_context_of_the_cause[1]>(5)test_function()
+    -> main()
+    (Pdb) down
+    > <doctest test.test_pdb.test_post_mortem_context_of_the_cause[0]>(9)main()
+    -> raise ValueError("With Cause, and cause has context") from ex
+    (Pdb) exit
+    """
+
+
 def test_post_mortem():
     """Test post mortem traceback debugging.