add more checking for group constructor.

Author: WindSoilder

exceptiongroup/_tests/test_exceptiongroup.py

@@ -12,6 +12,7 @@ def test_exception_group_init():
     assert group.exceptions == [memberA, memberB]
     assert group.message == "many error."
     assert group.sources == [str(memberA), str(memberB)]
+    assert group.args == ("many error.", [memberA, memberB], [str(memberA), str(memberB)])
 
 
 def test_exception_group_when_members_are_not_exceptions():