be consistent in our testing (#5409)

* be consistent in our testing

we don't use default_backend this way in our tests

* more black

Author: reaperhulk

tests/hazmat/primitives/test_pbkdf2hmac.py

@@ -7,7 +7,6 @@
 import pytest
 
 from cryptography.exceptions import AlreadyFinalized, InvalidKey, _Reasons
-from cryptography.hazmat.backends import default_backend
 from cryptography.hazmat.primitives import hashes
 from cryptography.hazmat.primitives.kdf.pbkdf2 import PBKDF2HMAC
 
@@ -16,47 +15,45 @@
 
 
 class TestPBKDF2HMAC(object):
-    def test_already_finalized(self):
-        kdf = PBKDF2HMAC(hashes.SHA1(), 20, b"salt", 10, default_backend())
+    def test_already_finalized(self, backend):
+        kdf = PBKDF2HMAC(hashes.SHA1(), 20, b"salt", 10, backend)
         kdf.derive(b"password")
         with pytest.raises(AlreadyFinalized):
             kdf.derive(b"password2")
 
-        kdf = PBKDF2HMAC(hashes.SHA1(), 20, b"salt", 10, default_backend())
+        kdf = PBKDF2HMAC(hashes.SHA1(), 20, b"salt", 10, backend)
         key = kdf.derive(b"password")
         with pytest.raises(AlreadyFinalized):
             kdf.verify(b"password", key)
 
-        kdf = PBKDF2HMAC(hashes.SHA1(), 20, b"salt", 10, default_backend())
+        kdf = PBKDF2HMAC(hashes.SHA1(), 20, b"salt", 10, backend)
         kdf.verify(b"password", key)
         with pytest.raises(AlreadyFinalized):
             kdf.verify(b"password", key)
 
-    def test_unsupported_algorithm(self):
+    def test_unsupported_algorithm(self, backend):
         with raises_unsupported_algorithm(_Reasons.UNSUPPORTED_HASH):
-            PBKDF2HMAC(
-                DummyHashAlgorithm(), 20, b"salt", 10, default_backend()
-            )
+            PBKDF2HMAC(DummyHashAlgorithm(), 20, b"salt", 10, backend)
 
-    def test_invalid_key(self):
-        kdf = PBKDF2HMAC(hashes.SHA1(), 20, b"salt", 10, default_backend())
+    def test_invalid_key(self, backend):
+        kdf = PBKDF2HMAC(hashes.SHA1(), 20, b"salt", 10, backend)
         key = kdf.derive(b"password")
 
-        kdf = PBKDF2HMAC(hashes.SHA1(), 20, b"salt", 10, default_backend())
+        kdf = PBKDF2HMAC(hashes.SHA1(), 20, b"salt", 10, backend)
         with pytest.raises(InvalidKey):
             kdf.verify(b"password2", key)
 
-    def test_unicode_error_with_salt(self):
+    def test_unicode_error_with_salt(self, backend):
         with pytest.raises(TypeError):
-            PBKDF2HMAC(hashes.SHA1(), 20, u"salt", 10, default_backend())
+            PBKDF2HMAC(hashes.SHA1(), 20, u"salt", 10, backend)
 
-    def test_unicode_error_with_key_material(self):
-        kdf = PBKDF2HMAC(hashes.SHA1(), 20, b"salt", 10, default_backend())
+    def test_unicode_error_with_key_material(self, backend):
+        kdf = PBKDF2HMAC(hashes.SHA1(), 20, b"salt", 10, backend)
         with pytest.raises(TypeError):
             kdf.derive(u"unicode here")
 
     def test_buffer_protocol(self, backend):
-        kdf = PBKDF2HMAC(hashes.SHA1(), 10, b"salt", 10, default_backend())
+        kdf = PBKDF2HMAC(hashes.SHA1(), 10, b"salt", 10, backend)
         data = bytearray(b"data")
         assert kdf.derive(data) == b"\xe9n\xaa\x81\xbbt\xa4\xf6\x08\xce"
 

tests/hazmat/primitives/test_x963_vectors.py

@@ -9,7 +9,6 @@
 
 import pytest
 
-from cryptography.hazmat.backends import default_backend
 from cryptography.hazmat.backends.interfaces import HashBackend
 from cryptography.hazmat.primitives import hashes
 from cryptography.hazmat.primitives.kdf.x963kdf import X963KDF
@@ -58,7 +57,7 @@ def test_x963(self, backend, vector):
             algorithm=hashfn(),
             length=key_data_len,
             sharedinfo=sharedinfo,
-            backend=default_backend(),
+            backend=backend,
         )
         xkdf.verify(key, key_data)