Check err_msg in tests

Author: vstinner

Lib/test/test_coroutines.py

@@ -2136,6 +2136,9 @@ async def func(): pass
             coro = None
             support.gc_collect()
 
+            self.assertEqual(cm.unraisable.err_msg,
+                             f"Exception ignored while finalizing "
+                             f"coroutine {coro_repr}")
             self.assertIn("was never awaited", str(cm.unraisable.exc_value))
 
     def test_for_assign_raising_stop_async_iteration(self):
@@ -2410,9 +2413,13 @@ async def corofn():
                 coro_repr = repr(coro)
 
                 # clear reference to the coroutine without awaiting for it
+                coro_repr = repr(coro)
                 del coro
                 support.gc_collect()
 
+                self.assertEqual(cm.unraisable.err_msg,
+                                 f"Exception ignored while finalizing "
+                                 f"coroutine {coro_repr}")
                 self.assertEqual(cm.unraisable.exc_type, ZeroDivisionError)
 
             del warnings._warn_unawaited_coroutine

Lib/test/test_exceptions.py

@@ -1678,9 +1678,13 @@ def __del__(self):
 
         obj = BrokenDel()
         with support.catch_unraisable_exception() as cm:
+            obj_repr = repr(type(obj).__del__)
             del obj
 
             gc_collect()  # For PyPy or other GCs.
+            self.assertEqual(cm.unraisable.err_msg,
+                             f"Exception ignored while calling "
+                             f"deallocator {obj_repr}")
             self.assertIsNotNone(cm.unraisable.exc_traceback)
 
     def test_unhandled(self):

Lib/test/test_generators.py

@@ -2664,14 +2664,17 @@ def printsolution(self, x):
 >>> with support.catch_unraisable_exception() as cm:
 ...     g = f()
 ...     next(g)
+...     gen_repr = repr(g)
 ...     del g
 ...
+...     cm.unraisable.err_msg == f'Exception ignored while closing generator {gen_repr}'
 ...     cm.unraisable.exc_type == RuntimeError
 ...     "generator ignored GeneratorExit" in str(cm.unraisable.exc_value)
 ...     cm.unraisable.exc_traceback is not None
 True
 True
 True
+True
 
 And errors thrown during closing should propagate: