This is required for the server test to work

moto/elbv2/urls.py

@@ -1,5 +1,10 @@
 from __future__ import unicode_literals
+from .responses import ELBV2Response
 
-url_bases = []
+url_bases = [
+    "https?://elasticloadbalancing.(.+).amazonaws.com",
+]
 
-url_paths = {}
+url_paths = {
+    '{0}/$': ELBV2Response.dispatch,
+}

tests/test_elbv2/test_server.py

@@ -8,7 +8,7 @@ Test the different server responses
 '''
 
 
-def test_elbv2_describe_instances():
+def test_elbv2_describe_load_balancers():
     backend = server.create_backend_app("elbv2")
     test_client = backend.test_client()