Tests & tweaks for ChoiceField

rest_framework/fields.py

@@ -769,7 +769,9 @@ class MultipleChoiceField(ChoiceField):
         ])
 
     def to_representation(self, value):
-        return [self.choice_strings_to_values[str(item)] for item in value]
+        return set([
+            self.choice_strings_to_values[str(item)] for item in value
+        ])
 
 
 # File types...

tests/test_fields.py

@@ -577,7 +577,9 @@ class TestMultipleChoiceField(FieldValues):
         'abc': ['Expected a list of items but got type `str`'],
         ('aircon', 'incorrect'): ['`incorrect` is not a valid choice.']
     }
-    outputs = {}
+    outputs = [
+        (['aircon', 'manual'], set(['aircon', 'manual']))
+    ]
     field = fields.MultipleChoiceField(
         choices=[
             ('aircon', 'AirCon'),