When using a test double for backends, always use one which really implements the interface

1 files changed, 6 insertions, 10 deletions

diff --git a/tests/hazmat/primitives/test_cmac.py b/tests/hazmat/primitives/test_cmac.py
index 49e2043e..c778ebee 100644
--- a/tests/hazmat/primitives/test_cmac.py
+++ b/tests/hazmat/primitives/test_cmac.py
@@ -21,7 +21,6 @@ import pytest
 
 import six
 
-from cryptography import utils
 from cryptography.exceptions import (
     AlreadyFinalized, InvalidSignature, _Reasons
 )
@@ -31,7 +30,8 @@ from cryptography.hazmat.primitives.ciphers.algorithms import (
 )
 from cryptography.hazmat.primitives.cmac import CMAC
 
-from tests.utils import (
+from ..backends.test_multibackend import DummyCMACBackend
+from ...utils import (
     load_nist_vectors, load_vectors_from_file, raises_unsupported_algorithm
 )
 
@@ -195,18 +195,14 @@ class TestCMAC(object):
 
 
 def test_copy():
-    @utils.register_interface(CMACBackend)
-    class PretendBackend(object):
-        pass
-
-    pretend_backend = PretendBackend()
+    backend = DummyCMACBackend([AES])
     copied_ctx = pretend.stub()
     pretend_ctx = pretend.stub(copy=lambda: copied_ctx)
     key = b"2b7e151628aed2a6abf7158809cf4f3c"
-    cmac = CMAC(AES(key), backend=pretend_backend, ctx=pretend_ctx)
+    cmac = CMAC(AES(key), backend=backend, ctx=pretend_ctx)
 
-    assert cmac._backend is pretend_backend
-    assert cmac.copy()._backend is pretend_backend
+    assert cmac._backend is backend
+    assert cmac.copy()._backend is backend
 
 
 def test_invalid_backend():