Added ElasticSearch backend to tests settings

runtests.py

@@ -62,7 +62,16 @@ if not settings.configured:
             'wagtail.wagtailsearch',
             'wagtail.wagtailredirects',
             'wagtail.tests',
-        ]
+        ],
+        WAGTAILSEARCH_BACKENDS={
+            'default': {
+                'BACKEND': 'wagtail.wagtailsearch.backends.db.DBSearch',
+            },
+            'elasticsearch': {
+                'BACKEND': 'wagtail.wagtailsearch.backends.elasticsearch.ElasticSearch',
+                'RUN_TESTS': True,
+            }
+        }
     )