bpo-46299: improve `test_descr.py` with stricter error handling (GH-30471)

(cherry picked from commit e63066cfed27511c9b786d61761f87f7a532571a)

Co-authored-by: Nikita Sobolev <mail@sobolevn.me>

diff --git a/Lib/test/test_descr.py b/Lib/test/test_descr.py
index 0e6a784c6c14babb5443bd873d6a54084cc22452..e5e9f4939699ee0580aff9c40afcf97ae0e76d67 100644 (file)
--- a/Lib/test/test_descr.py
+++ b/Lib/test/test_descr.py
@@ -2531,10 +2531,8 @@ order (MRO) for bases """
         m2instance.b = 2
         m2instance.a = 1
         self.assertEqual(m2instance.__dict__, "Not a dict!")
-        try:
+        with self.assertRaises(TypeError):
             dir(m2instance)
-        except TypeError:
-            pass
 
         # Two essentially featureless objects, (Ellipsis just inherits stuff
         # from object.
@@ -4013,7 +4011,7 @@ order (MRO) for bases """
         except TypeError:
             pass
         else:
-            assert 0, "best_base calculation found wanting"
+            self.fail("best_base calculation found wanting")
 
     def test_unsubclassable_types(self):
         with self.assertRaises(TypeError):
@@ -4399,6 +4397,8 @@ order (MRO) for bases """
             print("Oops!")
         except RuntimeError:
             pass
+        else:
+            self.fail("Didn't raise RuntimeError")
         finally:
             sys.stdout = test_stdout