Added all() method to get all document instances from a document. Extended the FileField's tests with testing on empty filefield.

mongoengine/queryset.py

@@ -239,6 +239,10 @@ class QuerySet(object):
         """
         return self.__call__(*q_objs, **query)
     
+    def all(self):
+        """Returns all documents."""
+        return self.__call__()
+
     @property
     def _collection(self):
         """Property that returns the collection object. This allows us to

tests/fields.py

@@ -675,6 +675,11 @@ class FieldTest(unittest.TestCase):
         StreamFile.drop_collection()
         SetFile.drop_collection()
 
+        # Make sure FileField is optional and not required
+        class DemoFile(Document):
+            file = FileField()
+        d = DemoFile.objects.create()
+
     def test_geo_indexes(self):
         """Ensure that indexes are created automatically for GeoPointFields.
         """