Resolve "Missing status and mother_id in offline reader"

Closes #80 (closed)

tests/test_offline.py

@@ -412,7 +412,7 @@ class TestOfflineTracks(unittest.TestCase):
         self.f = OFFLINE_FILE
         self.tracks = OFFLINE_FILE.events.tracks
         self.tracks_numucc = OFFLINE_NUMUCC
-        self.mc_tracks = OFFLINE_MC_TRACK
+        self.mc_tracks = OFFLINE_MC_TRACK.mc_tracks
         self.n_events = 10
         self.status = [100, 5, 11, 15, 1, 12, 12, 12, 12, 12]
         self.mother_id = [-1, -1, 1, 1, 0, 2, 5, 5, 6, 8]
@@ -441,7 +441,11 @@ class TestOfflineTracks(unittest.TestCase):
             
     def test_mother_id(self):
         assert np.allclose(self.mother_id, self.mc_tracks[1].mother_id[:10].tolist())
-         
+
+    def test_attribute_error_raised_for_older_files(self):
+        with self.assertRaises(AttributeError):
+            self.tracks[1].mother_id
+            
     def test_item_selection(self):
         self.assertListEqual(
             list(self.tracks[0].dir_z[:2]), [-0.872885221293917, -0.872885221293917]