Check we can add new elements to a ArraySequence loaded from disk

Author: MarcCote

nibabel/streamlines/tests/test_array_sequence.py

@@ -323,3 +323,6 @@ def test_save_and_load_arraysequence(self):
             assert_array_equal(loaded_seq._data, seq._data)
             assert_array_equal(loaded_seq._offsets, seq._offsets)
             assert_array_equal(loaded_seq._lengths, seq._lengths)
+
+            # Make sure we can add new elements to it.
+            loaded_seq.append(SEQ_DATA['data'][0])