Digg's unit test

searx/engines/digg.py

@@ -44,7 +44,7 @@ def response(resp):
 
     search_result = loads(resp.text)
 
-    if search_result['html'] == '':
+    if 'html' not in search_result or search_result['html'] == '':
         return results
 
     dom = html.fromstring(search_result['html'])

searx/tests/test_engines.py

@@ -1,6 +1,7 @@
 from searx.tests.engines.test_bing import *  # noqa
 from searx.tests.engines.test_dailymotion import *  # noqa
 from searx.tests.engines.test_deezer import *  # noqa
+from searx.tests.engines.test_digg import *  # noqa
 from searx.tests.engines.test_dummy import *  # noqa
 from searx.tests.engines.test_flickr import *  # noqa
 from searx.tests.engines.test_github import *  # noqa