Test more types of behavior in test_iter_options

tests/test_fields.py

@@ -1114,7 +1114,8 @@ class TestChoiceField(FieldValues):
         field = serializers.ChoiceField(
             choices=[
                 ('Numbers', ['integer', 'float']),
-                ('Strings', ['text', 'email', 'url'])
+                ('Strings', ['text', 'email', 'url']),
+                'boolean'
             ]
         )
         items = list(field.iter_options())
@@ -1132,6 +1133,8 @@ class TestChoiceField(FieldValues):
         assert items[7].value == 'url'
         assert items[8].end_option_group
 
+        assert items[9].value == 'boolean'
+
 
 class TestChoiceFieldWithType(FieldValues):
     """