gh-103395: Improve typing._GenericAlias.__dir__ coverage (GH-103396)

(cherry picked from commit a28e2ce)

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

Author: miss-islington

Lib/test/test_typing.py

@@ -851,6 +851,14 @@ def test_accepts_single_type(self):
         (*tuple[int],)
         Unpack[Tuple[int]]
 
+    def test_dir(self):
+        dir_items = set(dir(Unpack[Tuple[int]]))
+        for required_item in [
+            '__args__', '__parameters__', '__origin__',
+        ]:
+            with self.subTest(required_item=required_item):
+                self.assertIn(required_item, dir_items)
+
     def test_rejects_multiple_types(self):
         with self.assertRaises(TypeError):
             Unpack[Tuple[int], Tuple[str]]
@@ -1696,6 +1704,14 @@ def test_repr(self):
         u = Optional[str]
         self.assertEqual(repr(u), 'typing.Optional[str]')
 
+    def test_dir(self):
+        dir_items = set(dir(Union[str, int]))
+        for required_item in [
+            '__args__', '__parameters__', '__origin__',
+        ]:
+            with self.subTest(required_item=required_item):
+                self.assertIn(required_item, dir_items)
+
     def test_cannot_subclass(self):
         with self.assertRaises(TypeError):
             class C(Union):
@@ -1834,6 +1850,15 @@ def test_eq_hash(self):
         self.assertNotEqual(C, Callable[..., int])
         self.assertNotEqual(C, Callable)
 
+    def test_dir(self):
+        Callable = self.Callable
+        dir_items = set(dir(Callable[..., int]))
+        for required_item in [
+            '__args__', '__parameters__', '__origin__',
+        ]:
+            with self.subTest(required_item=required_item):
+                self.assertIn(required_item, dir_items)
+
     def test_cannot_instantiate(self):
         Callable = self.Callable
         with self.assertRaises(TypeError):
@@ -2146,6 +2171,14 @@ def test_repr(self):
         self.assertEqual(repr(Literal[None]), "typing.Literal[None]")
         self.assertEqual(repr(Literal[1, 2, 3, 3]), "typing.Literal[1, 2, 3]")
 
+    def test_dir(self):
+        dir_items = set(dir(Literal[1, 2, 3]))
+        for required_item in [
+            '__args__', '__parameters__', '__origin__',
+        ]:
+            with self.subTest(required_item=required_item):
+                self.assertIn(required_item, dir_items)
+
     def test_cannot_init(self):
         with self.assertRaises(TypeError):
             Literal()
@@ -7002,6 +7035,15 @@ def test_repr(self):
             "typing.Annotated[typing.List[int], 4, 5]"
         )
 
+    def test_dir(self):
+        dir_items = set(dir(Annotated[int, 4]))
+        for required_item in [
+            '__args__', '__parameters__', '__origin__',
+            '__metadata__',
+        ]:
+            with self.subTest(required_item=required_item):
+                self.assertIn(required_item, dir_items)
+
     def test_flatten(self):
         A = Annotated[Annotated[int, 4], 5]
         self.assertEqual(A, Annotated[int, 4, 5])
@@ -7701,6 +7743,15 @@ class MyClass: ...
         c = Concatenate[MyClass, P]
         self.assertNotEqual(c, Concatenate)
 
+    def test_dir(self):
+        P = ParamSpec('P')
+        dir_items = set(dir(Concatenate[int, P]))
+        for required_item in [
+            '__args__', '__parameters__', '__origin__',
+        ]:
+            with self.subTest(required_item=required_item):
+                self.assertIn(required_item, dir_items)
+
     def test_valid_uses(self):
         P = ParamSpec('P')
         T = TypeVar('T')
@@ -7969,10 +8020,18 @@ class Foo(Generic[T]):
             def bar(self):
                 pass
             baz = 3
+            __magic__ = 4
+
         # The class attributes of the original class should be visible even
         # in dir() of the GenericAlias. See bpo-45755.
-        self.assertIn('bar', dir(Foo[int]))
-        self.assertIn('baz', dir(Foo[int]))
+        dir_items = set(dir(Foo[int]))
+        for required_item in [
+            'bar', 'baz',
+            '__args__', '__parameters__', '__origin__',
+        ]:
+            with self.subTest(required_item=required_item):
+                self.assertIn(required_item, dir_items)
+        self.assertNotIn('__magic__', dir_items)
 
 
 class RevealTypeTests(BaseTestCase):