simplify how OpenSSL hash digests are requested

Author: picnixz

Lib/test/support/hashlib_helper.py

@@ -1,6 +1,7 @@
 import functools
 import hashlib
 import unittest
+from test.support.import_helper import import_module
 
 try:
     import _hashlib
@@ -68,3 +69,25 @@ def wrapper(*args, **kwargs):
     def decorator(func_or_class):
         return _decorate_func_or_class(func_or_class, decorator_func)
     return decorator
+
+
+def requires_openssl_hashdigest(digestname, *, usedforsecurity=True):
+    """Decorator raising SkipTest if an OpenSSL hashing algorithm is missing.
+
+    The hashing algorithm may be missing or blocked by a strict crypto policy.
+    """
+    def decorator_func(func):
+        @requires_hashlib()
+        @functools.wraps(func)
+        def wrapper(*args, **kwargs):
+            try:
+                _hashlib.new(digestname, usedforsecurity=usedforsecurity)
+            except ValueError:
+                msg = f"missing OpenSSL hash algorithm: {digestname!r}"
+                raise unittest.SkipTest(msg)
+            return func(*args, **kwargs)
+        return wrapper
+
+    def decorator(func_or_class):
+        return _decorate_func_or_class(func_or_class, decorator_func)
+    return decorator

Lib/test/test_hmac.py

@@ -358,8 +358,7 @@ def setUpClass(cls):
 
         for name in cls.ALGORITHMS:
             @property
-            @hashlib_helper.requires_hashlib()
-            @hashlib_helper.requires_hashdigest(name, openssl=True)
+            @hashlib_helper.requires_openssl_hashdigest(name)
             def func(self, *, __name=name):  # __name needed to bind 'name'
                 return getattr(_hashlib, f'openssl_{__name}')
             setattr(cls, name, func)
@@ -845,7 +844,7 @@ def test_repr(self):
         self.assertStartsWith(repr(h), "<hmac.HMAC object at")
 
 
-@hashlib_helper.requires_hashdigest('sha256', openssl=True)
+@hashlib_helper.requires_openssl_hashdigest('sha256')
 class OpenSSLSanityTestCase(ThroughOpenSSLAPIMixin, SanityTestCaseMixin,
                             unittest.TestCase):
 
@@ -897,8 +896,7 @@ def HMAC(self, key, msg=None):
         return self.hmac.HMAC(key, msg, digestmod='sha256')
 
 
-@hashlib_helper.requires_hashlib()
-@hashlib_helper.requires_hashdigest('sha256', openssl=True)
+@hashlib_helper.requires_openssl_hashdigest('sha256')
 class OpenSSLUpdateTestCase(UpdateTestCaseMixin, unittest.TestCase):
 
     def HMAC(self, key, msg=None):
@@ -988,8 +986,7 @@ def test_realcopy(self):
         self.assertNotEqual(id(h1._hmac), id(h2._hmac))
 
 
-@hashlib_helper.requires_hashlib()
-@hashlib_helper.requires_hashdigest('sha256', openssl=True)
+@hashlib_helper.requires_openssl_hashdigest('sha256')
 class OpenSSLCopyTestCase(ExtensionCopyTestCase, unittest.TestCase):
 
     def init(self, h):