Merge "Allow tags to be removed with update --existing"

2 files changed, 11 insertions, 1 deletions

diff --git a/heat/engine/api.py b/heat/engine/api.py
index 4cc6a6d9b..5ad560faa 100644
--- a/heat/engine/api.py
+++ b/heat/engine/api.py
@@ -60,7 +60,7 @@ def extract_args(params):
         kwargs[rpc_api.PARAM_ADOPT_STACK_DATA] = adopt_data
 
     tags = params.get(rpc_api.PARAM_TAGS)
-    if tags:
+    if tags is not None:
         if not isinstance(tags, list):
             raise ValueError(_('Invalid tags, not a list: %s') % tags)
 
diff --git a/heat/tests/engine/service/test_stack_update.py b/heat/tests/engine/service/test_stack_update.py
index f45adc35c..f340884b9 100644
--- a/heat/tests/engine/service/test_stack_update.py
+++ b/heat/tests/engine/service/test_stack_update.py
@@ -385,11 +385,21 @@ resources:
             self.ctx, stk, t, {}, None, None, None, api_args, None)
         self.assertEqual(['tag1'], updated_stack.tags)
 
+        # update clear old tags
+        api_args[rpc_api.STACK_TAGS] = []
+        _, _, updated_stack = self.man._prepare_stack_updates(
+            self.ctx, stk, t, {}, None, None, None, api_args, None)
+        self.assertEqual([], updated_stack.tags)
+
         # with new tags
         api_args[rpc_api.STACK_TAGS] = ['tag2']
         _, _, updated_stack = self.man._prepare_stack_updates(
             self.ctx, stk, t, {}, None, None, None, api_args, None)
         self.assertEqual(['tag2'], updated_stack.tags)
+        api_args[rpc_api.STACK_TAGS] = ['tag3']
+        _, _, updated_stack = self.man._prepare_stack_updates(
+            self.ctx, stk, t, {}, None, None, None, api_args, None)
+        self.assertEqual(['tag3'], updated_stack.tags)
 
         # with no PARAM_EXISTING flag and no tags
         del api_args[rpc_api.PARAM_EXISTING]