rename get_null_for_ecb to get_iv_for_ecb per alex's comments
diff --git a/tests/bindings/test_openssl.py b/tests/bindings/test_openssl.py
index c5927b7..f25236c 100644
--- a/tests/bindings/test_openssl.py
+++ b/tests/bindings/test_openssl.py
@@ -29,5 +29,5 @@
         """
         assert api.openssl_version_text().startswith("OpenSSL")
 
-    def test_get_null_for_ecb(self):
-        assert api.get_null_for_ecb() == api._ffi.NULL
+    def test_get_iv_for_ecb(self):
+        assert api.get_iv_for_ecb() == api._ffi.NULL