1 files changed, 11 insertions, 19 deletions
diff --git a/tests/hazmat/primitives/test_hmac.py b/tests/hazmat/primitives/test_hmac.py
index 83b18cbc..0e2fe688 100644
--- a/tests/hazmat/primitives/test_hmac.py
+++ b/tests/hazmat/primitives/test_hmac.py
@@ -4,11 +4,10 @@
 
 from __future__ import absolute_import, division, print_function
 
-import pretend
+import binascii
 
 import pytest
 
-from cryptography import utils
 from cryptography.exceptions import (
     AlreadyFinalized, InvalidSignature, _Reasons
 )
@@ -16,17 +15,10 @@ from cryptography.hazmat.backends.interfaces import HMACBackend
 from cryptography.hazmat.primitives import hashes, hmac
 
 from .utils import generate_base_hmac_test
-from ..backends.test_multibackend import DummyHMACBackend
+from ...doubles import DummyHashAlgorithm
 from ...utils import raises_unsupported_algorithm
 
 
-@utils.register_interface(hashes.HashAlgorithm)
-class UnsupportedDummyHash(object):
-    name = "unsupported-dummy-hash"
-    block_size = None
-    digest_size = None
-
-
 @pytest.mark.supported(
     only_if=lambda backend: backend.hmac_supported(hashes.MD5()),
     skip_message="Does not support MD5",
@@ -45,14 +37,6 @@ class TestHMAC(object):
         with pytest.raises(TypeError):
             h.update(u"\u00FC")
 
-    def test_copy_backend_object(self):
-        backend = DummyHMACBackend([hashes.SHA1])
-        copied_ctx = pretend.stub()
-        pretend_ctx = pretend.stub(copy=lambda: copied_ctx)
-        h = hmac.HMAC(b"key", hashes.SHA1(), backend=backend, ctx=pretend_ctx)
-        assert h._backend is backend
-        assert h.copy()._backend is backend
-
     def test_hmac_algorithm_instance(self, backend):
         with pytest.raises(TypeError):
             hmac.HMAC(b"key", hashes.SHA1, backend=backend)
@@ -95,7 +79,15 @@ class TestHMAC(object):
 
     def test_unsupported_hash(self, backend):
         with raises_unsupported_algorithm(_Reasons.UNSUPPORTED_HASH):
-            hmac.HMAC(b"key", UnsupportedDummyHash(), backend)
+            hmac.HMAC(b"key", DummyHashAlgorithm(), backend)
+
+    def test_buffer_protocol(self, backend):
+        key = bytearray(b"2b7e151628aed2a6abf7158809cf4f3c")
+        h = hmac.HMAC(key, hashes.SHA256(), backend)
+        h.update(bytearray(b"6bc1bee22e409f96e93d7e117393172a"))
+        assert h.finalize() == binascii.unhexlify(
+            b"a1bf7169c56a501c6585190ff4f07cad6e492a3ee187c0372614fb444b9fc3f0"
+        )
 
 
 def test_invalid_backend():