Fix handling of trailing slash to match API Gateway

API Gateway will not match a URI against a route that has a capture
group as the last path component if that capture group would be filled
with an empty string. Example:

With the route:
/resource/{name}

/resource/bob matches
/resource/    does not match

Previously local mode would match both URIs to that route, setting the
name parameter to an empty string.

closes aws#582

chalice/local.py

@@ -129,7 +129,7 @@ def match_route(self, url):
             url_parts = route_url.split('/')
             if len(parts) == len(url_parts):
                 for i, j in zip(parts, url_parts):
-                    if j.startswith('{') and j.endswith('}'):
+                    if j.startswith('{') and j.endswith('}') and i != '':
                         captured[j[1:-1]] = i
                         continue
                     if i != j:

tests/unit/test_local.py

@@ -486,6 +486,7 @@ def test_can_deny_unauthed_request(auth_handler):
     ('/foo/other', '/foo/{capture}'),
     ('/names/foo', '/names/{capture}'),
     ('/names/bar', '/names/{capture}'),
+    ('/names/', None),
     ('/nomatch', None),
     ('/names/bar/wrong', None),
     ('/a/z/c', '/a/{capture}/c'),