Added an extra test for EG loop rendering

Closes #35.

CHANGES.rst

@@ -8,7 +8,10 @@ This library adheres to `Semantic Versioning 2.0 <http://semver.org/>`_.
 - Fixed
   ``AttributeError: 'PatchedTracebackException' object has no attribute '__cause__'``
   on Python 3.10 (only) when a traceback is printed from an exception where an exception
-  group is set as the cause
+  group is set as the cause (#33)
+- Fixed a loop in exception groups being rendered incorrectly (#35)
+- Fixed the patched formatting functions (``format_exc()``etc.) not passing the
+  ``compact=True`` flag on Python 3.10 like the original functions do
 
 **1.0.0rc9**
 

tests/test_formatting.py

@@ -114,6 +114,44 @@ def test_exceptiongroup_as_cause(capsys: CaptureFixture) -> None:
     )
 
 
+def test_exceptiongroup_loop(capsys: CaptureFixture) -> None:
+    e0 = Exception("e0")
+    eg0 = ExceptionGroup("eg0", (e0,))
+    eg1 = ExceptionGroup("eg1", (eg0,))
+
+    try:
+        raise eg0 from eg1
+    except ExceptionGroup as exc:
+        sys.excepthook(type(exc), exc, exc.__traceback__)
+
+    lineno = test_exceptiongroup_loop.__code__.co_firstlineno + 6
+    module_prefix = "" if sys.version_info >= (3, 11) else "exceptiongroup."
+    output = capsys.readouterr().err
+    assert output == (
+        f"""\
+  | {module_prefix}ExceptionGroup: eg1 (1 sub-exception)
+  +-+---------------- 1 ----------------
+    | Exception Group Traceback (most recent call last):
+    |   File "{__file__}", line {lineno}, in test_exceptiongroup_loop
+    |     raise eg0 from eg1
+    | {module_prefix}ExceptionGroup: eg0 (1 sub-exception)
+    +-+---------------- 1 ----------------
+      | Exception: e0
+      +------------------------------------
+
+The above exception was the direct cause of the following exception:
+
+  + Exception Group Traceback (most recent call last):
+  |   File "{__file__}", line {lineno}, in test_exceptiongroup_loop
+  |     raise eg0 from eg1
+  | {module_prefix}ExceptionGroup: eg0 (1 sub-exception)
+  +-+---------------- 1 ----------------
+    | Exception: e0
+    +------------------------------------
+"""
+    )
+
+
 def test_exceptionhook_format_exception_only(capsys: CaptureFixture) -> None:
     try:
         raise_excgroup()