Fixed this test. It was passing for the wrong reason.

Shame on us for letting something without coverage land.
diff --git a/tests/hazmat/primitives/test_block.py b/tests/hazmat/primitives/test_block.py
index 4a8e88b..f6c44b4 100644
--- a/tests/hazmat/primitives/test_block.py
+++ b/tests/hazmat/primitives/test_block.py
@@ -47,10 +47,10 @@
         )
         assert isinstance(cipher.decryptor(), interfaces.CipherContext)
 
-    def test_instantiate_with_non_algorithm(self):
+    def test_instantiate_with_non_algorithm(self, backend):
         algorithm = object()
         with pytest.raises(TypeError):
-            Cipher(algorithm, mode=None)
+            Cipher(algorithm, mode=None, backend=backend)
 
 
 class TestCipherContext(object):