Added test_iter_options

rest_framework/fields.py

@@ -1192,20 +1192,25 @@ class ChoiceField(Field):
         """
         class StartOptionGroup(object):
             start_option_group = True
+            end_option_group = False
 
             def __init__(self, label):
                 self.label = label
 
         class EndOptionGroup(object):
+            start_option_group = False
             end_option_group = True
 
         class Option(object):
+            start_option_group = False
+            end_option_group = False
+
             def __init__(self, value, display_text):
                 self.value = value
                 self.display_text = display_text
 
         for key, value in self.grouped_choices.items():
-            if isinstance(value, (list, tuple)):
+            if isinstance(value, dict):
                 yield StartOptionGroup(label=key)
                 for sub_key, sub_value in value.items():
                     yield Option(value=sub_key, display_text=sub_value)

tests/test_fields.py

@@ -1107,6 +1107,31 @@ class TestChoiceField(FieldValues):
         output = field.run_validation(None)
         assert output is None
 
+    def test_iter_options(self):
+        """
+        iter_options() should return a list of options and option groups.
+        """
+        field = serializers.ChoiceField(
+            choices=[
+                ('Numbers', ['integer', 'float']),
+                ('Strings', ['text', 'email', 'url'])
+            ]
+        )
+        items = list(field.iter_options())
+
+        assert items[0].start_option_group
+        assert items[0].label == 'Numbers'
+        assert items[1].value == 'integer'
+        assert items[2].value == 'float'
+        assert items[3].end_option_group
+
+        assert items[4].start_option_group
+        assert items[4].label == 'Strings'
+        assert items[5].value == 'text'
+        assert items[6].value == 'email'
+        assert items[7].value == 'url'
+        assert items[8].end_option_group
+
 
 class TestChoiceFieldWithType(FieldValues):
     """