avocado.core.tree: Return correct path for the root node

Without this patch the root node path is ''. With this patch it returns
path-like '/'.
Signed-off-by: NLukáš Doktor <ldoktor@redhat.com>

avocado/core/tree.py

@@ -209,6 +209,8 @@ class TreeNode(object):
 
     def get_path(self, sep='/'):
         """ Get node path """
+        if not self.parent:
+            return sep + str(self.name)
         path = [str(self.name)]
         for node in self.iter_parents():
             path.append(str(node.name))
@@ -540,6 +542,8 @@ def path_parent(path):
     :return: the parent path as string.
     """
     parent = path.rpartition('/')[0]
+    if not parent:
+        return '/'
     return parent
 
 

selftests/all/unit/avocado/tree_unittest.py

@@ -190,10 +190,10 @@ class TestTree(unittest.TestCase):
 class TestPathParent(unittest.TestCase):
 
     def test_empty_string(self):
-        self.assertEqual(tree.path_parent(''), '')
+        self.assertEqual(tree.path_parent(''), '/')
 
     def test_on_root(self):
-        self.assertEqual(tree.path_parent('/'), '')
+        self.assertEqual(tree.path_parent('/'), '/')
 
     def test_direct_parent(self):
         self.assertEqual(tree.path_parent('/os/linux'), '/os')