Name presale index + unit test for URL names (#784)

* Name the default URL

If metrics collection is enabled, the index page of the site will fail
to load: without a name, the metrics middleware throws a TypeError.

* Test for names on all URLs

This test passes if all URLs have names. Without names, URLs will cause
the optional metrics middleware to throw a TypeError.

src/pretix/multidomain/maindomain_urlconf.py

@@ -15,7 +15,7 @@ presale_patterns_main = [
     url(r'', include((locale_patterns + [
         url(r'^(?P<organizer>[^/]+)/', include(organizer_patterns)),
         url(r'^(?P<organizer>[^/]+)/(?P<event>[^/]+)/', include(event_patterns)),
-        url(r'^$', TemplateView.as_view(template_name='pretixpresale/index.html'))
+        url(r'^$', TemplateView.as_view(template_name='pretixpresale/index.html'), name="index")
     ], 'presale')))
 ]
 

src/tests/base/test_urls.py

@@ -0,0 +1,41 @@
+from importlib import import_module
+
+from django.conf import settings
+from django.test import TestCase
+
+
+class URLTestCase(TestCase):
+    """
+    This test case tests for a name string on all URLs.  Unnamed
+    URLs will cause a TypeError in the metrics middleware.
+    """
+    pattern_attrs = ['urlpatterns', 'url_patterns']
+
+    def test_url_names(self):
+        urlconf = import_module(settings.ROOT_URLCONF)
+        nameless = self.find_nameless_urls(urlconf)
+        message = "URL regexes missing names: %s" % " ".join([n.regex.pattern for n in nameless])
+        self.assertIs(len(nameless), 0, message)
+
+    def find_nameless_urls(self, conf):
+        nameless = []
+        patterns = self.get_patterns(conf)
+        for u in patterns:
+            if self.has_patterns(u):
+                nameless.extend(self.find_nameless_urls(u))
+            else:
+                if u.name is None:
+                    nameless.append(u)
+        return nameless
+
+    def get_patterns(self, conf):
+        for pa in self.pattern_attrs:
+            if hasattr(conf, pa):
+                return getattr(conf, pa)
+        return []
+
+    def has_patterns(self, conf):
+        for pa in self.pattern_attrs:
+            if hasattr(conf, pa):
+                return True
+        return False