test: add test for anonymous user creation

This is linked to commit 46f4268461fa

cubicweb/pyramid/test/test_core.py

+from pyramid.config import Configurator
+
 from cubicweb.pyramid.test import PyramidCWTest
+from cubicweb.pyramid.core import includeme
 
 from cubicweb.view import View
 from cubicweb.web import Redirect
-from cubicweb import ValidationError
+from cubicweb import ValidationError, NoResultError
 
 
 class Redirector(View):
@@ -44,6 +47,38 @@ class CoreTest(PyramidCWTest):
         self.assertEqual(res.text, 'OK')
         self.assertEqual(res.status_int, 200)
 
+    def test_register_anonymous_user(self):
+        new_login = 'anon2'
+
+        # Make sure the user is not defined yet
+        with self.admin_access.cnx() as cnx:
+            new_anon = cnx.find('CWUser', login=new_login)
+            with self.assertRaises(NoResultError):
+                cnx.find('CWUser', login=new_login).one()
+
+        settings = {
+            'cubicweb.bwcompat': False,
+            'cubicweb.session.secret': 'test',
+        }
+        config = Configurator(settings=settings)
+        config.registry['cubicweb.repository'] = self.repo
+        config.registry['cubicweb.config'] = self.config
+
+        # Simulates changing anon in the all-in-one by changing the ApptestConfiguration used during
+        self.config.anonymous_credential = (new_login, 'password')
+
+        # Simulates instance restart (i.e. pyramid.core.include is called)
+        includeme(config)
+
+        with self.admin_access.cnx() as cnx:
+            # This raises if the user does not exist
+            new_anon = cnx.find('CWUser', login=new_login).one()
+
+            self.assertEquals(config.registry['cubicweb.anonymous_eid'], new_anon.eid)
+            # Erase the user to keep a clean database
+            new_anon.cw_delete()
+            cnx.commit()
+
 
 if __name__ == '__main__':
     from unittest import main