testing: switch to inserting deltas

As the comment in the test specifies, this was relying on storage backend
implementation details. We switch to inserting a raw delta, skipping the
regular insert path to ensure we have the desired outcome. This required
implementing support for handling deltas in the revlog testing code.

Differential Revision: https://phab.mercurial-scm.org/D5116

mercurial/testing/storage.py

@@ -952,13 +952,12 b' class ifiledatatests(basetestcase):'
         with self.assertRaises(error.StorageError):
             f.read(node1)
 
-        diff = mdiff.textdiff(fulltext1, fulltext2)
         node2 = storageutil.hashrevisionsha1(fulltext2, node1, nullid)
-        deltas = [(node2, node1, nullid, b'\x01' * 20, node1, diff, 0)]
 
-        # This /might/ fail on some backends.
         with self._maketransactionfn() as tr:
-            f.addgroup(deltas, lambda x: 0, tr)
+            delta = mdiff.textdiff(fulltext1, fulltext2)
+            self._addrawrevisionfn(f, tr, node2, node1, nullid,
+                                   2, delta=(1, delta))
 
         self.assertEqual(len(f), 3)
 

tests/test-storage.py

@@ -49,7 +49,8 b' def addrawrevision(self, fl, tr, node, p'
     if rawtext is not None:
         fl._revlog.addrawrevision(rawtext, tr, linkrev, p1, p2, node, flags)
     elif delta is not None:
-        raise error.Abort('support for storing raw deltas not yet supported')
+        fl._revlog.addrawrevision(rawtext, tr, linkrev, p1, p2, node, flags,
+                                  cachedelta=delta)
     else:
         raise error.Abort('must supply rawtext or delta arguments')