diff --git a/sphinx/testing/util.py b/sphinx/testing/util.py
index eee8c86b9b..bfa12ece8d 100644
--- a/sphinx/testing/util.py
+++ b/sphinx/testing/util.py
@@ -65,10 +65,14 @@ def assert_node(node, cls=None, xpath="", **kwargs):
                 if isinstance(cls[1], tuple):
                     assert_node(node, cls[1], xpath=xpath, **kwargs)
                 else:
+                    assert isinstance(node, nodes.Element), \
+                        'The node%s does not have any children' % xpath
                     assert len(node) == 1, \
                         'The node%s has %d child nodes, not one' % (xpath, len(node))
                     assert_node(node[0], cls[1:], xpath=xpath + "[0]", **kwargs)
         elif isinstance(cls, tuple):
+            assert isinstance(node, nodes.Element), \
+                'The node%s does not have any items' % xpath
             assert len(node) == len(cls), \
                 'The node%s has %d child nodes, not %r' % (xpath, len(node), len(cls))
             for i, nodecls in enumerate(cls):
@@ -80,10 +84,15 @@ def assert_node(node, cls=None, xpath="", **kwargs):
             assert isinstance(node, cls), \
                 'The node%s is not subclass of %r: %r' % (xpath, cls, node)
 
-    for key, value in kwargs.items():
-        assert key in node, 'The node%s does not have %r attribute: %r' % (xpath, key, node)
-        assert node[key] == value, \
-            'The node%s[%s] is not %r: %r' % (xpath, key, value, node[key])
+    if kwargs:
+        assert isinstance(node, nodes.Element), \
+            'The node%s does not have any attributes' % xpath
+
+        for key, value in kwargs.items():
+            assert key in node, \
+                'The node%s does not have %r attribute: %r' % (xpath, key, node)
+            assert node[key] == value, \
+                'The node%s[%s] is not %r: %r' % (xpath, key, value, node[key])
 
 
 def etree_parse(path):
diff --git a/tests/test_roles.py b/tests/test_roles.py
index 13b4e194d7..b7c94fc551 100644
--- a/tests/test_roles.py
+++ b/tests/test_roles.py
@@ -20,62 +20,62 @@ def test_samp():
     # normal case
     text = 'print 1+{variable}'
     ret, msg = emph_literal_role('samp', text, text, 0, Mock())
-    assert_node(ret, ([nodes.literal, ("print 1+",
-                                       [nodes.emphasis, "variable"])],))
+    assert_node(ret[0], [nodes.literal, ("print 1+",
+                                         [nodes.emphasis, "variable"])])
     assert msg == []
 
     # two emphasis items
     text = 'print {1}+{variable}'
     ret, msg = emph_literal_role('samp', text, text, 0, Mock())
-    assert_node(ret, ([nodes.literal, ("print ",
-                                       [nodes.emphasis, "1"],
-                                       "+",
-                                       [nodes.emphasis, "variable"])],))
+    assert_node(ret[0], [nodes.literal, ("print ",
+                                         [nodes.emphasis, "1"],
+                                         "+",
+                                         [nodes.emphasis, "variable"])])
     assert msg == []
 
     # empty curly brace
     text = 'print 1+{}'
     ret, msg = emph_literal_role('samp', text, text, 0, Mock())
-    assert_node(ret, ([nodes.literal, "print 1+{}"],))
+    assert_node(ret[0], [nodes.literal, "print 1+{}"])
     assert msg == []
 
     # half-opened variable
     text = 'print 1+{variable'
     ret, msg = emph_literal_role('samp', text, text, 0, Mock())
-    assert_node(ret, ([nodes.literal, "print 1+{variable"],))
+    assert_node(ret[0], [nodes.literal, "print 1+{variable"])
     assert msg == []
 
     # nested
     text = 'print 1+{{variable}}'
     ret, msg = emph_literal_role('samp', text, text, 0, Mock())
-    assert_node(ret, ([nodes.literal, ("print 1+",
-                                       [nodes.emphasis, "{variable"],
-                                       "}")],))
+    assert_node(ret[0], [nodes.literal, ("print 1+",
+                                         [nodes.emphasis, "{variable"],
+                                         "}")])
     assert msg == []
 
     # emphasized item only
     text = '{variable}'
     ret, msg = emph_literal_role('samp', text, text, 0, Mock())
-    assert_node(ret, ([nodes.literal, nodes.emphasis, "variable"],))
+    assert_node(ret[0], [nodes.literal, nodes.emphasis, "variable"])
     assert msg == []
 
     # escaping
     text = r'print 1+\{variable}'
     ret, msg = emph_literal_role('samp', text, text, 0, Mock())
-    assert_node(ret, ([nodes.literal, "print 1+{variable}"],))
+    assert_node(ret[0], [nodes.literal, "print 1+{variable}"])
     assert msg == []
 
     # escaping (2)
     text = r'print 1+\{{variable}\}'
     ret, msg = emph_literal_role('samp', text, text, 0, Mock())
-    assert_node(ret, ([nodes.literal, ("print 1+{",
-                                       [nodes.emphasis, "variable"],
-                                       "}")],))
+    assert_node(ret[0], [nodes.literal, ("print 1+{",
+                                         [nodes.emphasis, "variable"],
+                                         "}")])
     assert msg == []
 
     # escape a backslash
     text = r'print 1+\\{variable}'
     ret, msg = emph_literal_role('samp', text, text, 0, Mock())
-    assert_node(ret, ([nodes.literal, ("print 1+\\",
-                                       [nodes.emphasis, "variable"])],))
+    assert_node(ret[0], [nodes.literal, ("print 1+\\",
+                                         [nodes.emphasis, "variable"])])
     assert msg == []