Handling of exception groups

.circleci/config.yml

@@ -1,7 +1,7 @@
 version: 2.1
 
 orbs:
-  python: cjw296/python-ci@4.0.1
+  python: cjw296/python-ci@4.1
 
 jobs:
   check-package:

docs/api.txt

@@ -46,6 +46,8 @@ testfixtures.comparison
 
 .. autofunction:: testfixtures.comparison.compare_exception
 
+.. autofunction:: testfixtures.comparison.compare_exception_group
+
 .. autofunction:: testfixtures.comparison.compare_with_type
 
 .. autofunction:: testfixtures.comparison.compare_sequence

testfixtures/comparison.py

@@ -15,6 +15,7 @@
 import re
 
 from testfixtures import not_there, singleton
+from testfixtures.compat import PY_311_PLUS
 from testfixtures.resolve import resolve
 from testfixtures.utils import indent
 from testfixtures.mock import parent_name, mock_call
@@ -489,7 +490,25 @@ def _short_repr(obj) -> str:
     Path: compare_path,
     datetime: compare_with_fold,
     time: compare_with_fold,
-    }
+}
+
+if PY_311_PLUS:
+
+    def compare_exception_group(
+        x: BaseExceptionGroup, y: BaseExceptionGroup, context: 'CompareContext'
+    ) -> Optional[str]:
+        """
+        Compare the two supplied exception groups
+        """
+
+        x_msg, x_excs = x.args
+        y_msg, y_excs = y.args
+        msg_different = context.different(x_msg, y_msg, 'msg')
+        excs_different = context.different(x_excs, y_excs, 'excs')
+        if msg_different or excs_different:
+            return 'exception group not as expected:'
+
+    _registry[BaseExceptionGroup] = compare_exception_group
 
 
 def register(type_: type, comparer: Comparer):

testfixtures/tests/test_should_raise.py

@@ -1,8 +1,11 @@
 from textwrap import dedent
 
+import pytest
+
 from testfixtures import Comparison as C, ShouldRaise, should_raise
 from unittest import TestCase
 
+from ..compat import PY_311_PLUS
 from ..shouldraise import ShouldAssert
 
 
@@ -36,7 +39,6 @@ def test_wrong_text(self):
                 +assert False""")
 
 
-
 class TestShouldRaise(TestCase):
 
     def test_no_params(self):
@@ -301,4 +303,26 @@ def __repr__(self):
             with ShouldRaise(MessageError('foo')):
                 raise MessageError('foo', None)
 
+    @pytest.mark.skipif(not PY_311_PLUS, reason="requires python3.11 or higher")
+    def test_exception_group_okay(self):
+        with ShouldRaise(ExceptionGroup('foo', [Exception('bar')])):
+            raise ExceptionGroup('foo', [Exception('bar')])
+
+    @pytest.mark.skipif(not PY_311_PLUS, reason="requires python3.11 or higher")
+    def test_exception_group_different(self):
+        with ShouldAssert(
+                "exception group not as expected:\n\n"
+                "While comparing msg: 'fob' (expected) != 'foo' (raised)\n\n"
+                "While comparing excs: sequence not as expected:\n\n"
+                "same:\n"
+                "[]\n\n"
+                "expected:\n"
+                "[Exception('baz')]\n\n"
+                "raised:\n"
+                "[Exception('bar')]\n\n"
+                "While comparing excs[0]: "
+                "Exception('baz') (expected) != Exception('bar') (raised)"
+        ):
+            with ShouldRaise(ExceptionGroup('fob', [Exception('baz')])):
+                raise ExceptionGroup('foo', [Exception('bar')])