Added support for padding ANSI X.923
diff --git a/tests/hypothesis/test_padding.py b/tests/hypothesis/test_padding.py
index 21c9a23..29d726f 100644
--- a/tests/hypothesis/test_padding.py
+++ b/tests/hypothesis/test_padding.py
@@ -5,7 +5,7 @@
 from hypothesis import given
 from hypothesis.strategies import binary, integers
 
-from cryptography.hazmat.primitives.padding import PKCS7
+from cryptography.hazmat.primitives.padding import ANSIX923, PKCS7
 
 
 @given(integers(min_value=1, max_value=31), binary())
@@ -19,3 +19,14 @@
     padded = padder.update(data) + padder.finalize()
 
     assert unpadder.update(padded) + unpadder.finalize() == data
+
+
+@given(integers(min_value=1, max_value=31), binary())
+def test_ansix923(block_size, data):
+    a = ANSIX923(block_size=block_size * 8)
+    padder = a.padder()
+    unpadder = a.unpadder()
+
+    padded = padder.update(data) + padder.finalize()
+
+    assert unpadder.update(padded) + unpadder.finalize() == data