Convert X509ExtTests to use pytest-style tests (#564)

diff --git a/src/OpenSSL/rand.py b/src/OpenSSL/rand.py
index a22f9e5..8f51ad8 100644
--- a/src/OpenSSL/rand.py
+++ b/src/OpenSSL/rand.py
@@ -31,6 +31,7 @@
     See :manpage:`err(3)` for more information.
     """
 
+
 _raise_current_error = partial(_exception_from_error_queue, Error)
 
 _unspecified = object()
@@ -202,6 +203,7 @@
     """
     _lib.RAND_screen()
 
+
 if getattr(_lib, 'RAND_screen', None) is None:
     del screen