Merge pull request #849 from public/changeup-exceptions-2-electric-boogaloo

Use a single tagged exception instead of a hierarchy

1 files changed, 10 insertions, 0 deletions

diff --git a/tests/utils.py b/tests/utils.py
index 3e35970e..bdbf996f 100644
--- a/tests/utils.py
+++ b/tests/utils.py
@@ -14,11 +14,13 @@
 from __future__ import absolute_import, division, print_function
 
 import collections
+from contextlib import contextmanager
 
 import pytest
 
 import six
 
+from cryptography.exceptions import UnsupportedAlgorithm
 import cryptography_vectors
 
 
@@ -67,6 +69,14 @@ def check_backend_support(item):
                          "backend")
 
 
+@contextmanager
+def raises_unsupported_algorithm(reason):
+    with pytest.raises(UnsupportedAlgorithm) as exc_info:
+        yield exc_info
+
+    assert exc_info.value._reason is reason
+
+
 def load_vectors_from_file(filename, loader):
     with cryptography_vectors.open_vector_file(filename) as vector_file:
         return loader(vector_file)