[3.12] typing tests: remove some unnecessary uses of exec() (GH-119005) (#119039)

(cherry picked from commit a9328e2b6e)

Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>

Lib/test/test_typing.py

@@ -6635,24 +6635,16 @@ class CollectionsAbcTests(BaseTestCase):
         self.assertNotIsInstance(42, typing.Iterator)
 
     def test_awaitable(self):
-        ns = {}
+        async def foo() -> typing.Awaitable[int]:
-        exec(
+            return await AwaitableWrapper(42)
-            "async def foo() -> typing.Awaitable[int]:\n"
-            "    return await AwaitableWrapper(42)\n",
-            globals(), ns)
-        foo = ns['foo']
         g = foo()
         self.assertIsInstance(g, typing.Awaitable)
         self.assertNotIsInstance(foo, typing.Awaitable)
         g.send(None)  # Run foo() till completion, to avoid warning.
 
     def test_coroutine(self):
-        ns = {}
+        async def foo():
-        exec(
+            return
-            "async def foo():\n"
-            "    return\n",
-            globals(), ns)
-        foo = ns['foo']
         g = foo()
         self.assertIsInstance(g, typing.Coroutine)
         with self.assertRaises(TypeError):
@@ -6926,10 +6918,9 @@ class CollectionsAbcTests(BaseTestCase):
             typing.Generator[int, int, int]()
 
     def test_async_generator(self):
-        ns = {}
+        async def f():
-        exec("async def f():\n"
+             yield 42
-             "    yield 42\n", globals(), ns)
+        g = f()
-        g = ns['f']()
         self.assertIsSubclass(type(g), typing.AsyncGenerator)
 
     def test_no_async_generator_instantiation(self):
@@ -7016,9 +7007,8 @@ class CollectionsAbcTests(BaseTestCase):
             def athrow(self, typ, val=None, tb=None):
                 pass
 
-        ns = {}
+        async def g(): yield 0
-        exec('async def g(): yield 0', globals(), ns)
+
-        g = ns['g']
         self.assertIsSubclass(G, typing.AsyncGenerator)
         self.assertIsSubclass(G, typing.AsyncIterable)
         self.assertIsSubclass(G, collections.abc.AsyncGenerator)