Plugin-based panel group configuration

Panels can be added through plugin configuration, but it is broken
if the user can only use existing panel groups. This adds the
capability to create an empty panel group that can be used by panel
configuration to add itself to the group.

Change-Id: I28d6072fc05b3a4ef5a41cd68337a7864c560525
Closes-Bug: #1287981

openstack_dashboard/test/helpers.py

@@ -25,6 +25,7 @@ from django.conf import settings
 from django.contrib.auth.middleware import AuthenticationMiddleware  # noqa
 from django.contrib.messages.storage import default_storage  # noqa
 from django.core.handlers import wsgi
+from django.core import urlresolvers
 from django import http
 from django.test.client import RequestFactory  # noqa
 from django.utils.importlib import import_module  # noqa
@@ -47,6 +48,8 @@ import mox
 from openstack_auth import user
 from openstack_auth import utils
 
+from horizon import base
+from horizon import conf
 from horizon import middleware
 from horizon.test import helpers as horizon_helpers
 
@@ -415,3 +418,54 @@ def my_custom_sort(flavor):
         'm1.massive': 2,
     }
     return sort_order[flavor.name]
+
+
+class PluginTestCase(TestCase):
+    """The ``PluginTestCase`` class is for use with tests which deal with the
+    pluggable dashboard and panel configuration, it takes care of backing up
+    and restoring the Horizon configuration.
+    """
+    def setUp(self):
+        super(PluginTestCase, self).setUp()
+        self.old_horizon_config = conf.HORIZON_CONFIG
+        conf.HORIZON_CONFIG = conf.LazySettings()
+        base.Horizon._urls()
+        # Trigger discovery, registration, and URLconf generation if it
+        # hasn't happened yet.
+        self.client.get("/")
+        # Store our original dashboards
+        self._discovered_dashboards = base.Horizon._registry.keys()
+        # Gather up and store our original panels for each dashboard
+        self._discovered_panels = {}
+        for dash in self._discovered_dashboards:
+            panels = base.Horizon._registry[dash]._registry.keys()
+            self._discovered_panels[dash] = panels
+
+    def tearDown(self):
+        super(PluginTestCase, self).tearDown()
+        conf.HORIZON_CONFIG = self.old_horizon_config
+        # Destroy our singleton and re-create it.
+        base.HorizonSite._instance = None
+        del base.Horizon
+        base.Horizon = base.HorizonSite()
+        # Reload the convenience references to Horizon stored in __init__
+        reload(import_module("horizon"))
+        # Re-register our original dashboards and panels.
+        # This is necessary because autodiscovery only works on the first
+        # import, and calling reload introduces innumerable additional
+        # problems. Manual re-registration is the only good way for testing.
+        for dash in self._discovered_dashboards:
+            base.Horizon.register(dash)
+            for panel in self._discovered_panels[dash]:
+                dash.register(panel)
+        self._reload_urls()
+
+    def _reload_urls(self):
+        """Clears out the URL caches, reloads the root urls module, and
+        re-triggers the autodiscovery mechanism for Horizon. Allows URLs
+        to be re-calculated after registering new dashboards. Useful
+        only for testing and should never be used on a live site.
+        """
+        urlresolvers.clear_url_caches()
+        reload(import_module(settings.ROOT_URLCONF))
+        base.Horizon._urls()