the output of RAND_bytes is os.urandom's result

1 files changed, 14 insertions, 0 deletions

diff --git a/tests/hazmat/bindings/test_openssl.py b/tests/hazmat/bindings/test_openssl.py
index 75a8e3f1..207fece9 100644
--- a/tests/hazmat/bindings/test_openssl.py
+++ b/tests/hazmat/bindings/test_openssl.py
@@ -4,6 +4,8 @@
 
 from __future__ import absolute_import, division, print_function
 
+import os
+
 import pytest
 
 from cryptography.hazmat.bindings.openssl.binding import Binding
@@ -92,6 +94,18 @@ class TestOpenSSL(object):
         with pytest.raises(RuntimeError):
             b._register_osrandom_engine()
 
+    def test_actual_osrandom_bytes(self, monkeypatch):
+        sample_data = (b"\x01\x02\x03\x04" * 4)
+        length = len(sample_data)
+        def notrandom(size):
+            assert size == length
+            return sample_data
+        monkeypatch.setattr(os, "urandom", notrandom)
+        b = Binding()
+        buf = b.ffi.new("char[]", length)
+        b.lib.RAND_bytes(buf, length)
+        assert b.ffi.buffer(buf)[0:length] == sample_data
+
     def test_ssl_ctx_options(self):
         # Test that we're properly handling 32-bit unsigned on all platforms.
         b = Binding()