diff -r d909c44d29e1 -r a269fa55467e mercurial/testing/storage.py
--- a/mercurial/testing/storage.py	Mon Sep 24 12:49:17 2018 -0700
+++ b/mercurial/testing/storage.py	Mon Sep 24 13:35:50 2018 -0700
@@ -122,15 +122,6 @@
         with self.assertRaises(error.LookupError):
             f.children(b'\x01' * 20)
 
-        self.assertEqual(f.deltaparent(nullrev), nullrev)
-
-        for i in range(-5, 5):
-            if i == nullrev:
-                continue
-
-            with self.assertRaises(IndexError):
-                f.deltaparent(i)
-
     def testsinglerevision(self):
         f = self._makefilefn()
         with self._maketransactionfn() as tr:
@@ -200,8 +191,6 @@
 
         self.assertEqual(f.children(node), [])
 
-        self.assertEqual(f.deltaparent(0), nullrev)
-
     def testmultiplerevisions(self):
         fulltext0 = b'x' * 1024
         fulltext1 = fulltext0 + b'y'
@@ -313,10 +302,6 @@
         self.assertEqual(f.children(node1), [node2])
         self.assertEqual(f.children(node2), [])
 
-        self.assertEqual(f.deltaparent(0), nullrev)
-        self.assertEqual(f.deltaparent(1), 0)
-        self.assertEqual(f.deltaparent(2), 1)
-
     def testmultipleheads(self):
         f = self._makefilefn()