Check return code of SSL_[CTX_]set_alpn_protos (#993)

* check return code of SSL_CTX_set_alpn_protos, fix #992

* paint it black!

* fix line lengths as well :upside_down_face:

1 files changed, 9 insertions, 0 deletions

diff --git a/tests/test_ssl.py b/tests/test_ssl.py
index 8fdcae2..27f2d43 100644
--- a/tests/test_ssl.py
+++ b/tests/test_ssl.py
@@ -1888,6 +1888,15 @@ class TestApplicationLayerProtoNegotiation(object):
         assert server.get_alpn_proto_negotiated() == b"spdy/2"
         assert client.get_alpn_proto_negotiated() == b"spdy/2"
 
+    def test_alpn_call_failure(self):
+        """
+        SSL_CTX_set_alpn_protos does not like to be called with an empty
+        protocols list. Ensure that we produce a user-visible error.
+        """
+        context = Context(SSLv23_METHOD)
+        with pytest.raises(Error):
+            context.set_alpn_protos([])
+
     def test_alpn_set_on_connection(self):
         """
         The same as test_alpn_success, but setting the ALPN protocols on