RendertileSet: Round-robin the four top-level subtrees

test/test_rendertileset.py

@@ -1,6 +1,7 @@
 import unittest
 
 from overviewer_core.tileset import iterate_base4, RendertileSet
+from overviewer_core.util import roundrobin
 
 class RendertileSetTest(unittest.TestCase):
     # If you change this definition, you must also change the hard-coded
@@ -196,6 +197,65 @@ class RendertileSetTest(unittest.TestCase):
 
         self.assertRaises(StopIteration, next, iterator)
 
+    def test_posttraverse_roundrobin(self):
+        """Test a round-robin post-traversal of the tree's dirty tiles"""
+        # Expect these results in this proper order.
+        expected_lists = [
+            [
+                (0,0,3),
+                (0,0,1),
+                (0,0,2),
+                (0,0,0),
+                (0,0),
+                (0,),
+            ],
+            [
+                (1,2,0),
+                (1,2),
+
+                (1,0,3),
+                (1,0),
+
+                (1,1,3),
+                (1,1),
+                (1,),
+            ],
+            [
+                (2,1,1),
+                (2,1,0),
+                (2,1,3),
+                (2,1,2),
+                (2,1),
+
+                (2,0,1),
+                (2,0,3),
+                (2,0,0),
+                (2,0,2),
+                (2,0),
+
+                (2,3,1),
+                (2,3,0),
+                (2,3,3),
+                (2,3,2),
+                (2,3),
+
+                (2,2,1),
+                (2,2,0),
+                (2,2,3),
+                (2,2,2),
+                (2,2),
+                (2,),
+            ],
+        ]
+        expected_list = list(roundrobin(expected_lists)) + [ () ]
+
+        iterator = iter(self.tree.posttraversal(robin=True))
+        from itertools import izip
+        for expected, actual in izip(expected_list, iterator):
+            self.assertEqual(actual, expected)
+
+        self.assertRaises(StopIteration, next, iterator)
+
     def test_count_all(self):
         """Tests getting a count of all tiles (render tiles plus upper tiles)