From e50767cfca081681f527c54d3f6652d11e95e758 Mon Sep 17 00:00:00 2001
From: David Lord <davidism@gmail.com>
Date: Thu, 20 Apr 2017 08:52:37 -0700
Subject: [PATCH] add test for build error special values

---
 tests/test_basic.py | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/tests/test_basic.py b/tests/test_basic.py
index 76efd6e2..abce3ad4 100644
--- a/tests/test_basic.py
+++ b/tests/test_basic.py
@@ -1131,6 +1131,23 @@ def test_build_error_handler_reraise():
         pytest.raises(BuildError, flask.url_for, 'not.existing')
 
 
+def test_url_for_passes_special_values_to_build_error_handler():
+    app = flask.Flask(__name__)
+
+    @app.url_build_error_handlers.append
+    def handler(error, endpoint, values):
+        assert values == {
+            '_external': False,
+            '_anchor': None,
+            '_method': None,
+            '_scheme': None,
+        }
+        return 'handled'
+
+    with app.test_request_context():
+        flask.url_for('/')
+
+
 def test_custom_converters():
     from werkzeug.routing import BaseConverter