bpo-43908: Mark ssl, hash, and hmac types as immutable (GH-25792)

Signed-off-by: Christian Heimes <christian@python.org>

3 files changed, 31 insertions, 0 deletions

diff --git a/Lib/test/test_hashlib.py b/Lib/test/test_hashlib.py
index a515d3a..ad2ed69 100644
--- a/Lib/test/test_hashlib.py
+++ b/Lib/test/test_hashlib.py
@@ -926,6 +926,15 @@ class HashLibTestCase(unittest.TestCase):
         ):
             HASHXOF()
 
+    def test_readonly_types(self):
+        for algorithm, constructors in self.constructors_to_test.items():
+            # all other types have DISALLOW_INSTANTIATION
+            for constructor in constructors:
+                hash_type = type(constructor())
+                with self.subTest(hash_type=hash_type):
+                    with self.assertRaisesRegex(TypeError, "immutable type"):
+                        hash_type.value = False
+
 
 class KDFTests(unittest.TestCase):
 
diff --git a/Lib/test/test_hmac.py b/Lib/test/test_hmac.py
index 22d74e9..964acd0 100644
--- a/Lib/test/test_hmac.py
+++ b/Lib/test/test_hmac.py
@@ -444,6 +444,9 @@ class ConstructorTestCase(unittest.TestCase):
         ):
             C_HMAC()
 
+        with self.assertRaisesRegex(TypeError, "immutable type"):
+            C_HMAC.value = None
+
     @unittest.skipUnless(sha256_module is not None, 'need _sha256')
     def test_with_sha256_module(self):
         h = hmac.HMAC(b"key", b"hash this!", digestmod=sha256_module.sha256)
diff --git a/Lib/test/test_ssl.py b/Lib/test/test_ssl.py
index f2b26c4..acb64f1 100644
--- a/Lib/test/test_ssl.py
+++ b/Lib/test/test_ssl.py
@@ -345,6 +345,25 @@ class BasicSocketTests(unittest.TestCase):
         ssl.OP_NO_TLSv1_2
         self.assertEqual(ssl.PROTOCOL_TLS, ssl.PROTOCOL_SSLv23)
 
+    def test_ssl_types(self):
+        ssl_types = [
+            _ssl._SSLContext,
+            _ssl._SSLSocket,
+            _ssl.MemoryBIO,
+            _ssl.Certificate,
+            _ssl.SSLSession,
+            _ssl.SSLError,
+        ]
+        for ssl_type in ssl_types:
+            with self.subTest(ssl_type=ssl_type):
+                with self.assertRaisesRegex(TypeError, "immutable type"):
+                    ssl_type.value = None
+        with self.assertRaisesRegex(
+            TypeError,
+            "cannot create '_ssl.Certificate' instances"
+        ):
+            _ssl.Certificate()
+
     def test_private_init(self):
         with self.assertRaisesRegex(TypeError, "public constructor"):
             with socket.socket() as s: