Update test_dictcomps, test_userdict

Lib/test/test_dictcomps.py

@@ -1,5 +1,8 @@
+import traceback
 import unittest
 
+from test.support import BrokenIter
+
 # For scope testing.
 g = "Global variable"
 
@@ -72,8 +75,7 @@ class DictComprehensionTest(unittest.TestCase):
         self.assertEqual(actual, expected)
         self.assertEqual(v, "Local variable")
 
-    # TODO: RUSTPYTHON
-    @unittest.expectedFailure
+    @unittest.expectedFailure  # TODO: RUSTPYTHON
     def test_illegal_assignment(self):
         with self.assertRaisesRegex(SyntaxError, "cannot assign"):
             compile("{x: y for y, x in ((1, 2), (3, 4))} = 5", "<test>",
@@ -129,6 +131,41 @@ class DictComprehensionTest(unittest.TestCase):
         self.assertEqual({i: i*i for i in [*range(4)]}, expected)
         self.assertEqual({i: i*i for i in (*range(4),)}, expected)
 
+    def test_exception_locations(self):
+        # The location of an exception raised from __init__ or
+        # __next__ should should be the iterator expression
+        def init_raises():
+            try:
+                {x:x for x in BrokenIter(init_raises=True)}
+            except Exception as e:
+                return e
+
+        def next_raises():
+            try:
+                {x:x for x in BrokenIter(next_raises=True)}
+            except Exception as e:
+                return e
+
+        def iter_raises():
+            try:
+                {x:x for x in BrokenIter(iter_raises=True)}
+            except Exception as e:
+                return e
+
+        for func, expected in [(init_raises, "BrokenIter(init_raises=True)"),
+                               (next_raises, "BrokenIter(next_raises=True)"),
+                               (iter_raises, "BrokenIter(iter_raises=True)"),
+                              ]:
+            with self.subTest(func):
+                exc = func()
+                f = traceback.extract_tb(exc.__traceback__)[0]
+                indent = 16
+                co = func.__code__
+                self.assertEqual(f.lineno, co.co_firstlineno + 2)
+                self.assertEqual(f.end_lineno, co.co_firstlineno + 2)
+                self.assertEqual(f.line[f.colno - indent : f.end_colno - indent],
+                                 expected)
+
 
 if __name__ == "__main__":
     unittest.main()

Lib/test/test_userdict.py

@@ -1,6 +1,6 @@
 # Check every path through every method of UserDict
 
-from test import mapping_tests, support
+from test import mapping_tests
 import unittest
 import collections
 
@@ -166,7 +166,7 @@ class UserDictTest(mapping_tests.TestHashMappingProtocol):
 
     def test_missing(self):
         # Make sure UserDict doesn't have a __missing__ method
-        self.assertEqual(hasattr(collections.UserDict, "__missing__"), False)
+        self.assertNotHasAttr(collections.UserDict, "__missing__")
         # Test several cases:
         # (D) subclass defines __missing__ method returning a value
         # (E) subclass defines __missing__ method raising RuntimeError
@@ -213,11 +213,7 @@ class UserDictTest(mapping_tests.TestHashMappingProtocol):
         else:
             self.fail("g[42] didn't raise KeyError")
 
-    # Decorate existing test with recursion limit, because
-    # the test is for C structure, but `UserDict` is a Python structure.
-    test_repr_deep = support.infinite_recursion(25)(
-        mapping_tests.TestHashMappingProtocol.test_repr_deep,
-    )
+    test_repr_deep = mapping_tests.TestHashMappingProtocol.test_repr_deep
 
 
 if __name__ == "__main__":