diff --git a/api/tests/chain/test_tile.py b/api/tests/chain/test_tile.py
index 097d6ad1..a006a34e 100644
--- a/api/tests/chain/test_tile.py
+++ b/api/tests/chain/test_tile.py
@@ -2,7 +2,7 @@ import unittest
 
 from PIL import Image
 
-from onnx_web.chain.tile import complete_tile, get_tile_grads, needs_tile
+from onnx_web.chain.tile import complete_tile, generate_tile_spiral, get_tile_grads, needs_tile
 from onnx_web.params import Size
 
 
@@ -63,9 +63,30 @@ class TestTileGrads(unittest.TestCase):
     self.assertEqual(grad_x, [0, 1, 1, 0])
     self.assertEqual(grad_y, [1, 1, 1, 1])
 
-
   def test_horizontal_edge_tile(self):
     grad_x, grad_y = get_tile_grads(0, 32, 8, 8, 64)
 
     self.assertEqual(grad_x, [1, 1, 1, 1])
     self.assertEqual(grad_y, [0, 1, 1, 0])
+
+
+class TestGenerateTileSpiral(unittest.TestCase):
+  def test_spiral_complete(self):
+    tiles = generate_tile_spiral(16, 16, 8, 0.0)
+
+    self.assertEqual(len(tiles), 4)
+    self.assertEqual(tiles, [(0, 0), (8, 0), (8, 8), (0, 8)])
+
+  def test_spiral_no_overlap(self):
+    tiles = generate_tile_spiral(64, 64, 8, 0.0)
+
+    self.assertEqual(len(tiles), 64)
+    self.assertEqual(tiles[0:4], [(0, 0), (8, 0), (16, 0), (24, 0)])
+    self.assertEqual(tiles[-5:-1], [(16, 24), (24, 24), (32, 24), (32, 32)])
+
+  def test_spiral_50_overlap(self):
+    tiles = generate_tile_spiral(64, 64, 8, 0.5)
+
+    self.assertEqual(len(tiles), 225)
+    self.assertEqual(tiles[0:4], [(0, 0), (4, 0), (8, 0), (12, 0)])
+    self.assertEqual(tiles[-5:-1], [(32, 32), (28, 32), (24, 32), (24, 28)])