Properly support negative steps

Author: Jordan Woods

tableauserverclient/server/query.py

@@ -43,6 +43,12 @@ def __getitem__(self, k):
                 start += self.total_available
             if stop < 0:
                 stop += self.total_available
+            if start < stop and step < 0:
+                # Since slicing is left inclusive and right exclusive, shift
+                # the start and stop values by 1 to keep that behavior
+                start, stop = stop - 1, start - 1
+                slice_stop = stop if stop > 0 else None
+                k = slice(start, slice_stop, step)
 
             k_range = range(start, stop, step)
             if all(i in page_range for i in k_range):

test/test_request_option.py

@@ -246,6 +246,13 @@ def test_slicing_queryset(self):
             self.assertEqual(3, len(all_views[2:5]))
             self.assertEqual(3, len(all_views[-3:]))
             self.assertEqual(3, len(all_views[-6:-3]))
+            self.assertEqual(3, len(all_views[3:6:-1]))
+            self.assertEqual(3, len(all_views[6:3:-1]))
+            self.assertEqual(10, len(all_views[::-1]))
+            self.assertEqual(
+                all_views[3:6],
+                list(reversed(all_views[3:6:-1]))
+            )
 
             self.assertEqual(all_views[-3].id, "2df55de2-3a2d-4e34-b515-6d4e70b830e9")