SDK-765: Make multivalue a tuple, remove redundant parsing

Author: echarrod

yoti_python_sdk/multivalue.py

@@ -10,15 +10,13 @@ def parse(multi_value_bytes):
     parsed_multi_value = proto.multi_value(multi_value_bytes)
 
     for multi_value_item in parsed_multi_value.values:
-        value = attribute_parser.value_based_on_content_type(multi_value_item.data, multi_value_item.content_type)
-
-        if value.content_type == proto.CT_MULTI_VALUE:
-            multi_value_list.append(parse(value))
-        else:
-            multi_value_list.append(value)
+        multi_value_list.append(
+            attribute_parser.value_based_on_content_type(
+                multi_value_item.data,
+                multi_value_item.content_type))
 
     return multi_value_list
 
 
 def filter_values(values, type_to_filter):
-    return list(filter(lambda v: isinstance(v, type_to_filter), values))
+    return tuple(filter(lambda v: isinstance(v, type_to_filter), values))

yoti_python_sdk/tests/test_multivalue.py

@@ -41,3 +41,14 @@ def test_multi_value_filter_string():
 
     assert len(filtered_list) == 1
     assert filtered_list[0] is string_value
+
+
+def test_multi_value_filter_is_immutable():
+    original_string_value = "string_value"
+    multi_value = [0, original_string_value]
+
+    filtered_list = multivalue.filter_values(multi_value, str)
+
+    filtered_list[0] == "changed_string_value"
+
+    assert filtered_list[0] == original_string_value