DFS in right order when not starting at the provided node

When the dfs iteration is requested to start at the provided
nodes children make sure that we create the stack in the same
way as we do its children to ensure that the DFS iteration
order is maintained correctly in this situation.

Change-Id: I9d5e3a46b4d2349ab1662a634d635b2052be4a55

2 files changed, 10 insertions, 2 deletions

diff --git a/taskflow/tests/unit/test_types.py b/taskflow/tests/unit/test_types.py
index 4daea4b..83d938d 100644
--- a/taskflow/tests/unit/test_types.py
+++ b/taskflow/tests/unit/test_types.py
@@ -142,6 +142,15 @@ class TreeTest(test.TestCase):
         self.assertEqual(set(['animal', 'reptile', 'mammal', 'horse',
                               'primate', 'monkey', 'human']), set(things))
 
+    def test_dfs_itr_order(self):
+        root = self._make_species()
+        things = list([n.item for n in root.dfs_iter(include_self=True)])
+        self.assertEqual(['animal', 'mammal', 'horse', 'primate',
+                          'monkey', 'human', 'reptile'], things)
+        things = list([n.item for n in root.dfs_iter(include_self=False)])
+        self.assertEqual(['mammal', 'horse', 'primate',
+                          'monkey', 'human', 'reptile'], things)
+
 
 class StopWatchTest(test.TestCase):
     def setUp(self):
diff --git a/taskflow/types/tree.py b/taskflow/types/tree.py
index 7777044..2386bc9 100644
--- a/taskflow/types/tree.py
+++ b/taskflow/types/tree.py
@@ -40,8 +40,7 @@ class _DFSIter(object):
         if self.include_self:
             stack.append(self.root)
         else:
-            for child_node in self.root:
-                stack.append(child_node)
+            stack.extend(self.root.reverse_iter())
         while stack:
             node = stack.pop()
             # Visit the node.