Add workaround for functions in translation

Currently if translation data is function and translation path
runs over unresolved function's value (i.e. intermediate data is
function), translation works incorrectly and raises AttributeError.
This workaround makes translation skip rules, where translation values
contains inside functions.

NOTE: This patch is not solve issues, described by Zane Bitter in [1],
just add workaround for current mechanism. Also, it doesn't affect
destination values, just intermediate, which currently cannot be safely
resolved.

[1] https://bugs.launchpad.net/heat/+bug/1620859

Change-Id: I5d7f8d3a615590325d38702b21f224ff3de33315
Closes-bug: #1630214

heat/engine/translation.py

@@ -230,6 +230,11 @@ class TranslationRule(object):
     def translate_property(self, path, data, return_value=False, value=None,
                            value_data=None, value_key=None,
                            client_resolve=True):
+        if isinstance(data, function.Function):
+            if return_value:
+                raise AttributeError('No chance to translate value due to '
+                                     'value is function. Skip translation.')
+            return
         current_key = path[0]
         if len(path) <= 1:
             if return_value:

heat/tests/test_translation_rule.py

@@ -862,6 +862,44 @@ class TestTranslationRule(common.HeatTestCase):
         self.assertEqual({'source': param, 'destination': ''},
                          data)
 
+    def test_property_get_attr_translation_successfully_skipped(self):
+        schema = {
+            'source': properties.Schema(
+                properties.Schema.LIST,
+                schema=properties.Schema(
+                    properties.Schema.MAP,
+                    schema={
+                        'sub-source': properties.Schema(
+                            properties.Schema.STRING
+                        )
+                    }
+                )
+            ),
+            'destination': properties.Schema(
+                properties.Schema.STRING
+            )}
+
+        class DummyStack(dict):
+            pass
+
+        class rsrc(object):
+            pass
+
+        stack = DummyStack(res=rsrc())
+        attr_func = cfn_funcs.GetAtt(stack, 'Fn::GetAtt',
+                                     ['res', 'sub-sources'])
+
+        data = {'source': attr_func, 'destination': ''}
+        props = properties.Properties(schema, data)
+
+        rule = translation.TranslationRule(
+            props,
+            translation.TranslationRule.REPLACE,
+            ['source', 'sub-sources'],
+            value_path=['destination'])
+        rule.execute_rule()
+        self.assertEqual({'source': attr_func, 'destination': ''}, props.data)
+
     def test_list_list_add_translation_rule(self):
         schema = {
             'far': properties.Schema(