Fixed a bug in CorrectMaps.get_npoints(), which would return 1

when npoints=0.

common/lib/capa/capa/correctmap.py

@@ -117,7 +117,7 @@ class CorrectMap(object):
             Otherwise, return 0 points """
         if self.is_correct(answer_id):
             npoints = self.get_property(answer_id, 'npoints')
-            return npoints if npoints else 1
+            return npoints if npoints is not None else 1
         else:
             return 0
 

common/lib/capa/capa/tests/test_correctmap.py

@@ -69,6 +69,7 @@ class CorrectMapTest(unittest.TestCase):
         # 2) correct, None points
         # 3) incorrect, 5 points
         # 4) incorrect, None points
+        # 5) correct, 0 points
         self.cmap.set(answer_id='1_2_1',
                     correctness='correct',
                     npoints=5)
@@ -85,6 +86,10 @@ class CorrectMapTest(unittest.TestCase):
                     correctness='incorrect',
                     npoints=None)
 
+        self.cmap.set(answer_id='5_2_1',
+                    correctness='correct',
+                    npoints=0)
+
         # Assert that we get the expected points
         # If points assigned and correct --> npoints
         # If no points assigned and correct --> 1 point
@@ -93,6 +98,7 @@ class CorrectMapTest(unittest.TestCase):
         self.assertEqual(self.cmap.get_npoints('2_2_1'), 1)
         self.assertEqual(self.cmap.get_npoints('3_2_1'), 0)
         self.assertEqual(self.cmap.get_npoints('4_2_1'), 0)
+        self.assertEqual(self.cmap.get_npoints('5_2_1'), 0)
 
 
     def test_set_overall_message(self):