ListType preserves the order of the input

The ListType class returns a list of items in a string.
The list was not guaranteed to be the same order as in the string;
this patch changes it so that the order is preserved.

Related-Bug: #1715541
Change-Id: Iefab751d34e97f460b6d63316eb38085e4eb1154

ironic/api/controllers/v1/types.py

@@ -162,12 +162,15 @@ class ListType(wtypes.UserType):
         """Validate and convert the input to a ListType.
 
         :param value: A comma separated string of values
-        :returns: A list of unique values, whose order is not guaranteed.
+        :returns: A list of unique values (lower-cased), maintaining the
+                  same order
         """
-        items = [v.strip().lower() for v in six.text_type(value).split(',')]
+        items = []
-        # filter() to remove empty items
+        for v in six.text_type(value).split(','):
-        # set() to remove duplicated items
+            v_norm = v.strip().lower()
-        return list(set(filter(None, items)))
+            if v_norm and v_norm not in items:
+                items.append(v_norm)
+        return items
 
     @staticmethod
     def frombasetype(value):

ironic/tests/unit/api/controllers/v1/test_types.py

@@ -277,14 +277,14 @@ class TestListType(base.TestCase):
 
     def test_list_type(self):
         v = types.ListType()
-        self.assertItemsEqual(['foo', 'bar'], v.validate('foo,bar'))
+        self.assertEqual(['foo', 'bar'], v.validate('foo,bar'))
-        self.assertItemsEqual(['cat', 'meow'], v.validate("cat  ,  meow"))
+        self.assertNotEqual(['bar', 'foo'], v.validate('foo,bar'))
-        self.assertItemsEqual(['spongebob', 'squarepants'],
+
-                              v.validate("SpongeBob,SquarePants"))
+        self.assertEqual(['cat', 'meow'], v.validate("cat  ,  meow"))
-        self.assertItemsEqual(['foo', 'bar'],
+        self.assertEqual(['spongebob', 'squarepants'],
-                              v.validate("foo, ,,bar"))
+                         v.validate("SpongeBob,SquarePants"))
-        self.assertItemsEqual(['foo', 'bar'],
+        self.assertEqual(['foo', 'bar'], v.validate("foo, ,,bar"))
-                              v.validate("foo,foo,foo,bar"))
+        self.assertEqual(['foo', 'bar'], v.validate("foo,foo,foo,bar"))
         self.assertIsInstance(v.validate('foo,bar'), list)