raise an exception if you try to use a HashContext after finalize is called.

1 files changed, 11 insertions, 0 deletions

diff --git a/tests/hazmat/primitives/test_hashes.py b/tests/hazmat/primitives/test_hashes.py
index 6cdb0a07..a5c440b8 100644
--- a/tests/hazmat/primitives/test_hashes.py
+++ b/tests/hazmat/primitives/test_hashes.py
@@ -19,6 +19,7 @@ import pytest
 
 import six
 
+from cryptography import exceptions
 from cryptography.hazmat.bindings import _default_backend
 from cryptography.hazmat.primitives import hashes
 
@@ -51,6 +52,16 @@ class TestHashContext(object):
         with pytest.raises(TypeError):
             hashes.Hash(hashes.SHA1)
 
+    def test_raises_after_finalize(self):
+        h = hashes.Hash(hashes.SHA1())
+        h.finalize()
+
+        with pytest.raises(exceptions.AlreadyFinalized):
+            h.update(b"foo")
+
+        with pytest.raises(exceptions.AlreadyFinalized):
+            h.copy()
+
 
 class TestSHA1(object):
     test_SHA1 = generate_base_hash_test(