ManifoldTable: Fix bug where OrientableCuspedCensus(tets=3)[100:] would return a non-empty list.

Author: unhyperbolic

src/snappy/database.py

@@ -221,7 +221,9 @@ def __getitem__(self, index):
                     base_query += 'where %s ' % self._filter
                 query = base_query + 'order by id limit 1 offset %d' % start
                 start_id = self._cursor.execute(query).fetchone()
-                if start_id is not None:
+                if start_id is None:
+                    conditions.append('false')
+                else:
                     conditions.append('id >= %d' % start_id[0])
                 query = base_query + 'order by id limit 1 offset %d' % stop
                 stop_id = self._cursor.execute(query).fetchone()

src/snappy/tests/misc.py

@@ -74,12 +74,35 @@
 >>> 'singularity_index' in c.keys()
 False
 
+ManifoldTable
+-------------
+
+>>> len(OrientableCuspedCensus(tets=3))
+9
+>>> len(OrientableCuspedCensus(tets=3)[0:3])
+3
+>>> len(OrientableCuspedCensus(tets=3)[1:3])
+2
+>>> list(OrientableCuspedCensus(tets=3)[1:3])
+[m007(0,0), m009(0,0)]
+>>> list(OrientableCuspedCensus(tets=3)[4:])
+[m011(0,0), m015(0,0), m016(0,0), m017(0,0), m019(0,0)]
+>>> list(OrientableCuspedCensus(tets=3)[4:][1:3])
+[m015(0,0), m016(0,0)]
+>>> list(OrientableCuspedCensus(tets=3)[4:100])
+[m011(0,0), m015(0,0), m016(0,0), m017(0,0), m019(0,0)]
+>>> list(OrientableCuspedCensus(tets=3)[100:])
+[]
+
 """
 
 if not __doc__:
     raise Exception("doc string with tests was not recognized.")
 
-from .. import Manifold, ManifoldHP, Triangulation, TriangulationHP, NonorientableCuspedCensus
+from .. import (
+    Manifold, ManifoldHP,
+    Triangulation, TriangulationHP,
+    OrientableCuspedCensus, NonorientableCuspedCensus)
 
 def my_cusp_orientabilities(T):
     T._testing_compute_cusp_orientabilities()