Merge pull request #132 from taigaio/bug/1392/get-neighbors-for-empty-queryset

Fixing bug when selecting neighbors in an empty queryset of related elements

taiga/base/neighbors.py

@@ -87,7 +87,7 @@ def get_neighbors(obj, results_set=None):
 
     :return: Tuple `<left neighbor>, <right neighbor>`. Left and right neighbors can be `None`.
     """
-    if results_set is None:
+    if results_set is None or results_set.count() == 0:
         results_set = type(obj).objects.get_queryset()
     try:
         left = _left_candidates(obj, results_set).reverse()[0]

tests/integration/test_neighbors.py

@@ -137,6 +137,18 @@ class TestIssues:
         assert neighbors.left == issue3
         assert neighbors.right == issue1
 
+    def test_empty_related_queryset(self):
+        project = f.ProjectFactory.create()
+
+        issue1 = f.IssueFactory.create(project=project)
+        issue2 = f.IssueFactory.create(project=project)
+        issue3 = f.IssueFactory.create(project=project)
+
+        neighbors = n.get_neighbors(issue2, Issue.objects.none())
+
+        assert neighbors.left == issue3
+        assert neighbors.right == issue1
+
     def test_ordering_by_severity(self):
         project = f.ProjectFactory.create()
         severity1 = f.SeverityFactory.create(project=project, order=1)