time to remove commoncrypto, fare thee well (#3551)

* time to remove commoncrypto, fare thee well

* remove even more

* update the changelog

* remove more things

* don't need this function

* remove CAST5 CTR tests since that was only supported in commoncrypto

* assert a thing

2 files changed, 2 insertions, 20 deletions

diff --git a/tests/hazmat/primitives/test_cast5.py b/tests/hazmat/primitives/test_cast5.py
index 59af84f5..ec51659d 100644
--- a/tests/hazmat/primitives/test_cast5.py
+++ b/tests/hazmat/primitives/test_cast5.py
@@ -82,20 +82,3 @@ class TestCAST5ModeCFB(object):
         lambda key, **kwargs: algorithms.CAST5(binascii.unhexlify((key))),
         lambda iv, **kwargs: modes.CFB(binascii.unhexlify(iv))
     )
-
-
-@pytest.mark.supported(
-    only_if=lambda backend: backend.cipher_supported(
-        algorithms.CAST5(b"\x00" * 16), modes.CTR(b"\x00" * 8)
-    ),
-    skip_message="Does not support CAST5 CTR",
-)
-@pytest.mark.requires_backend_interface(interface=CipherBackend)
-class TestCAST5ModeCTR(object):
-    test_CTR = generate_encrypt_test(
-        load_nist_vectors,
-        os.path.join("ciphers", "CAST5"),
-        ["cast5-ctr.txt"],
-        lambda key, **kwargs: algorithms.CAST5(binascii.unhexlify((key))),
-        lambda iv, **kwargs: modes.CTR(binascii.unhexlify(iv))
-    )
diff --git a/tests/hazmat/primitives/utils.py b/tests/hazmat/primitives/utils.py
index 59326367..b8200123 100644
--- a/tests/hazmat/primitives/utils.py
+++ b/tests/hazmat/primitives/utils.py
@@ -47,10 +47,9 @@ def generate_encrypt_test(param_loader, path, file_names, cipher_factory,
 
 
 def encrypt_test(backend, cipher_factory, mode_factory, params):
-    if not backend.cipher_supported(
+    assert backend.cipher_supported(
         cipher_factory(**params), mode_factory(**params)
-    ):
-        pytest.skip("cipher/mode combo is unsupported by this backend")
+    )
 
     plaintext = params["plaintext"]
     ciphertext = params["ciphertext"]