Add test case for missing HiPS tiles

hips/tiles/tests/test_fetch.py

@@ -1,20 +1,35 @@
 # Licensed under a 3-clause BSD style license - see LICENSE.rst
 import pytest
 from astropy.tests.helper import remote_data
-from numpy.testing import assert_allclose
+from numpy.testing import assert_allclose, assert_equal
 from ..fetch import fetch_tiles
 from ..survey import HipsSurveyProperties
 from ..tile import HipsTileMeta
 
 TILE_FETCH_TEST_CASES = [
     dict(
         tile_indices=[69623, 69627, 69628, 69629, 69630, 69631],
+        is_missing=[False, False, False, False, False, False],
         tile_format='fits',
         order=7,
         url='http://alasky.unistra.fr/DSS/DSS2Merged/properties',
         progress_bar=True,
         data=[2101, 1945, 1828, 1871, 2079, 2336],
     ),
+    dict(
+        tile_indices=[69623,
+                      9999999,  # missing
+                      69628,
+                      9999999,  # missing
+                      9999999,  # missing
+                      69631],
+        is_missing=[False, True, False, True, True, False],
+        tile_format='fits',
+        order=7,
+        url='http://alasky.unistra.fr/DSS/DSS2Merged/properties',
+        progress_bar=True,
+        data=[2101, 0, 1828, 0, 0, 2336],
+    ),
 ]
 
 
@@ -42,3 +57,6 @@ def test_fetch_tiles(pars):
 
     for idx, val in enumerate(pars['data']):
         assert_allclose(tiles[idx].data[0][5], val)
+
+    for idx, val in enumerate(pars['is_missing']):
+        assert_equal(tiles[idx].is_missing, val)

hips/tiles/tile.py

@@ -156,7 +156,7 @@ class HipsTile:
     raw_data : `bytes`
         Raw data (copy of bytes from file)
     is_missing : `bool`
-        To check whether the tile is missing or not
+        Specifies whether the tile is missing or not
 
     Examples
     --------