1 files changed, 12 insertions, 0 deletions
diff --git a/tests/hazmat/primitives/test_ciphers.py b/tests/hazmat/primitives/test_ciphers.py
index d9f83535..e1f5dbc3 100644
--- a/tests/hazmat/primitives/test_ciphers.py
+++ b/tests/hazmat/primitives/test_ciphers.py
@@ -17,10 +17,15 @@ import binascii
 
 import pytest
 
+from cryptography.exceptions import UnsupportedInterface
+
+from cryptography.hazmat.primitives import ciphers
 from cryptography.hazmat.primitives.ciphers.algorithms import (
     AES, Camellia, TripleDES, Blowfish, ARC4, CAST5, IDEA
 )
 
+from cryptography.hazmat.primitives.ciphers.modes import ECB
+
 
 class TestAES(object):
     @pytest.mark.parametrize(("key", "keysize"), [
@@ -120,3 +125,10 @@ class TestIDEA(object):
     def test_invalid_key_size(self):
         with pytest.raises(ValueError):
             IDEA(b"\x00" * 17)
+
+
+def test_invalid_backend():
+    pretend_backend = object()
+
+    with pytest.raises(UnsupportedInterface):
+        ciphers.Cipher(AES(b"AAAAAAAAAAAAAAAA"), ECB, pretend_backend)