--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/tests/testlib/ext-sidedata-5.py	Fri Feb 19 11:24:50 2021 +0100
@@ -0,0 +1,81 @@
+# coding: utf8
+# ext-sidedata-5.py - small extension to test (differently still) the sidedata
+# logic
+#
+# Simulates a server for a simple sidedata exchange.
+#
+# Copyright 2021 Raphaël Gomès <rgomes@octobus.net>
+#
+# This software may be used and distributed according to the terms of the
+# GNU General Public License version 2 or any later version.
+
+from __future__ import absolute_import
+
+import hashlib
+import struct
+
+from mercurial import (
+    extensions,
+    revlog,
+)
+
+
+from mercurial.revlogutils import sidedata as sidedatamod
+
+
+def compute_sidedata_1(repo, revlog, rev, sidedata, text=None):
+    sidedata = sidedata.copy()
+    if text is None:
+        text = revlog.revision(rev)
+    sidedata[sidedatamod.SD_TEST1] = struct.pack('>I', len(text))
+    return sidedata
+
+
+def compute_sidedata_2(repo, revlog, rev, sidedata, text=None):
+    sidedata = sidedata.copy()
+    if text is None:
+        text = revlog.revision(rev)
+    sha256 = hashlib.sha256(text).digest()
+    sidedata[sidedatamod.SD_TEST2] = struct.pack('>32s', sha256)
+    return sidedata
+
+
+def reposetup(ui, repo):
+    # Sidedata keys happen to be the same as the categories, easier for testing.
+    for kind in (b'changelog', b'manifest', b'filelog'):
+        repo.register_sidedata_computer(
+            kind,
+            sidedatamod.SD_TEST1,
+            (sidedatamod.SD_TEST1,),
+            compute_sidedata_1,
+        )
+        repo.register_sidedata_computer(
+            kind,
+            sidedatamod.SD_TEST2,
+            (sidedatamod.SD_TEST2,),
+            compute_sidedata_2,
+        )
+
+    # We don't register sidedata computers because we don't care within these
+    # tests
+    repo.register_wanted_sidedata(sidedatamod.SD_TEST1)
+    repo.register_wanted_sidedata(sidedatamod.SD_TEST2)
+
+
+def wrapaddrevision(
+    orig, self, text, transaction, link, p1, p2, *args, **kwargs
+):
+    if kwargs.get('sidedata') is None:
+        kwargs['sidedata'] = {}
+    sd = kwargs['sidedata']
+    ## let's store some arbitrary data just for testing
+    # text length
+    sd[sidedatamod.SD_TEST1] = struct.pack('>I', len(text))
+    # and sha2 hashes
+    sha256 = hashlib.sha256(text).digest()
+    sd[sidedatamod.SD_TEST2] = struct.pack('>32s', sha256)
+    return orig(self, text, transaction, link, p1, p2, *args, **kwargs)
+
+
+def extsetup(ui):
+    extensions.wrapfunction(revlog.revlog, 'addrevision', wrapaddrevision)