4 files changed, 66 insertions, 5 deletions
diff --git a/tests/hazmat/backends/test_commoncrypto.py b/tests/hazmat/backends/test_commoncrypto.py
index 6bb0ede0..eb61a574 100644
--- a/tests/hazmat/backends/test_commoncrypto.py
+++ b/tests/hazmat/backends/test_commoncrypto.py
@@ -29,8 +29,8 @@ from ...utils import raises_unsupported_algorithm
 @utils.register_interface(interfaces.CipherAlgorithm)
 class DummyCipher(object):
     name = "dummy-cipher"
-    block_size = 128
-    digest_size = None
+    block_size = None
+    key_size = None
 
 
 @pytest.mark.skipif("commoncrypto" not in
diff --git a/tests/hazmat/backends/test_openssl.py b/tests/hazmat/backends/test_openssl.py
index ebd8686c..bc6a2bac 100644
--- a/tests/hazmat/backends/test_openssl.py
+++ b/tests/hazmat/backends/test_openssl.py
@@ -439,8 +439,7 @@ class TestOpenSSLCMAC(object):
     def test_unsupported_cipher(self):
         @utils.register_interface(BlockCipherAlgorithm)
         class FakeAlgorithm(object):
-            def __init__(self):
-                self.block_size = 64
+            block_size = 64
 
         with raises_unsupported_algorithm(_Reasons.UNSUPPORTED_CIPHER):
             backend.create_cmac_ctx(FakeAlgorithm())
diff --git a/tests/hazmat/primitives/test_ec.py b/tests/hazmat/primitives/test_ec.py
index e6a9146c..6aea58a5 100644
--- a/tests/hazmat/primitives/test_ec.py
+++ b/tests/hazmat/primitives/test_ec.py
@@ -71,7 +71,6 @@ class DummySignatureAlgorithm(object):
     algorithm = None
 
 
-@utils.register_interface(EllipticCurveBackend)
 class DeprecatedDummyECBackend(object):
     def elliptic_curve_private_key_from_numbers(self, numbers):
         return b"private_key"
diff --git a/tests/test_interfaces.py b/tests/test_interfaces.py
new file mode 100644
index 00000000..b988abee
--- /dev/null
+++ b/tests/test_interfaces.py
@@ -0,0 +1,63 @@
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+# implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import abc
+
+import pytest
+
+import six
+
+from cryptography.utils import InterfaceNotImplemented, verify_interface
+
+
+class TestVerifyInterface(object):
+    def test_verify_missing_method(self):
+        @six.add_metaclass(abc.ABCMeta)
+        class SimpleInterface(object):
+            @abc.abstractmethod
+            def method(self):
+                """A simple method"""
+
+        class NonImplementer(object):
+            pass
+
+        with pytest.raises(InterfaceNotImplemented):
+            verify_interface(SimpleInterface, NonImplementer)
+
+    def test_different_arguments(self):
+        @six.add_metaclass(abc.ABCMeta)
+        class SimpleInterface(object):
+            @abc.abstractmethod
+            def method(self, a):
+                """Method with one argument"""
+
+        class NonImplementer(object):
+            def method(self):
+                """Method with no arguments"""
+
+        with pytest.raises(InterfaceNotImplemented):
+            verify_interface(SimpleInterface, NonImplementer)
+
+    def test_handles_abstract_property(self):
+        @six.add_metaclass(abc.ABCMeta)
+        class SimpleInterface(object):
+            @abc.abstractproperty
+            def property(self):
+                """An abstract property"""
+
+        class NonImplementer(object):
+            @property
+            def property(self):
+                """A concrete property"""
+
+        verify_interface(SimpleInterface, NonImplementer)