Merge pull request #1851 from bagerard/fix_IndexError_iter_while_modif_list

fix BaseList.__iter__ operator + minor improvements

AUTHORS

@@ -246,3 +246,4 @@ that much better:
  * Renjianxin (https://github.com/Davidrjx)
  * Erdenezul Batmunkh (https://github.com/erdenezul)
  * Andy Yankovsky (https://github.com/werat)
+ * Bastien Gérard (https://github.com/bagerard)

mongoengine/base/datastructures.py

@@ -128,8 +128,8 @@ class BaseList(list):
         return value
 
     def __iter__(self):
-        for i in six.moves.range(self.__len__()):
-            yield self[i]
+        for v in super(BaseList, self).__iter__():
+            yield v
 
     def __setitem__(self, key, value, *args, **kwargs):
         if isinstance(key, slice):
@@ -138,7 +138,7 @@ class BaseList(list):
             self._mark_as_changed(key)
         return super(BaseList, self).__setitem__(key, value)
 
-    def __delitem__(self, key, *args, **kwargs):
+    def __delitem__(self, key):
         self._mark_as_changed()
         return super(BaseList, self).__delitem__(key)
 
@@ -187,7 +187,7 @@ class BaseList(list):
         self._mark_as_changed()
         return super(BaseList, self).remove(*args, **kwargs)
 
-    def reverse(self, *args, **kwargs):
+    def reverse(self):
         self._mark_as_changed()
         return super(BaseList, self).reverse()
 

tests/test_datastructures.py

@@ -1,6 +1,21 @@
 import unittest
 
-from mongoengine.base.datastructures import StrictDict
+from mongoengine.base.datastructures import StrictDict, BaseList
+
+
+class TestBaseList(unittest.TestCase):
+
+    def test_iter_simple(self):
+        values = [True, False, True, False]
+        base_list = BaseList(values, instance=None, name='my_name')
+        self.assertEqual(values, list(base_list))
+
+    def test_iter_allow_modification_while_iterating_withou_error(self):
+        # regular list allows for this, thus this subclass must comply to that
+        base_list = BaseList([True, False, True, False], instance=None, name='my_name')
+        for idx, val in enumerate(base_list):
+            if val:
+                base_list.pop(idx)
 
 
 class TestStrictDict(unittest.TestCase):