--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/tests/test-push-race.t	Sat May 27 22:24:58 2017 +0200
@@ -0,0 +1,191 @@
+============================================================================================
+Test cases where there are race condition between two clients pushing to the same repository
+============================================================================================
+
+This file tests cases where two clients push to a server at the same time. The
+"raced" client is done preparing it push bundle when the "racing" client
+perform its push. The "raced" client starts its actual push after the "racing"
+client push is fully complete.
+
+A set of extension and shell functions ensures this scheduling.
+
+  $ cat >> delaypush.py << EOF
+  > """small extension orchestrate push race
+  > 
+  > Client with the extensions will create a file when ready and get stuck until
+  > a file is created."""
+  > 
+  > import atexit
+  > import errno
+  > import os
+  > import time
+  > 
+  > from mercurial import (
+  >     exchange,
+  >     extensions,
+  > )
+  > 
+  > def delaypush(orig, pushop):
+  >     # notify we are done preparing
+  >     readypath = pushop.repo.ui.config('delaypush', 'ready-path', None)
+  >     if readypath is not None:
+  >         with open(readypath, 'w') as r:
+  >             r.write('foo')
+  >         pushop.repo.ui.status('wrote ready: %s\n' % readypath)
+  >     # now wait for the other process to be done
+  >     watchpath = pushop.repo.ui.config('delaypush', 'release-path', None)
+  >     if watchpath is not None:
+  >         pushop.repo.ui.status('waiting on: %s\n' % watchpath)
+  >         limit = 100
+  >         while 0 < limit and not os.path.exists(watchpath):
+  >             limit -= 1
+  >             time.sleep(0.1)
+  >         if limit <= 0:
+  >             repo.ui.warn('exiting without watchfile: %s' % watchpath)
+  >         else:
+  >             # delete the file at the end of the push
+  >             def delete():
+  >                 try:
+  >                     os.unlink(watchpath)
+  >                 except OSError as exc:
+  >                     if exc.errno != errno.ENOENT:
+  >                         raise
+  >             atexit.register(delete)
+  >     return orig(pushop)
+  > 
+  > def uisetup(ui):
+  >     extensions.wrapfunction(exchange, '_pushbundle2', delaypush)
+  > EOF
+
+  $ waiton () {
+  >     # wait for a file to be created (then delete it)
+  >     count=100
+  >     while [ ! -f $1 ] ;
+  >     do
+  >         sleep 0.1;
+  >         count=`expr $count - 1`;
+  >         if [ $count -lt 0 ];
+  >         then
+  >              break
+  >         fi;
+  >     done
+  >     [ -f $1 ] || echo "ready file still missing: $1"
+  >     rm -f $1
+  > }
+
+  $ release () {
+  >     # create a file and wait for it be deleted
+  >     count=100
+  >     touch $1
+  >     while [ -f $1 ] ;
+  >     do
+  >         sleep 0.1;
+  >         count=`expr $count - 1`;
+  >         if [ $count -lt 0 ];
+  >         then
+  >              break
+  >         fi;
+  >     done
+  >     [ ! -f $1 ] || echo "delay file still exist: $1"
+  > }
+
+  $ cat >> $HGRCPATH << EOF
+  > [ui]
+  > ssh = python "$TESTDIR/dummyssh"
+  > # simplify output
+  > logtemplate = {node|short} {desc} ({branch})
+  > [alias]
+  > graph = log -G --rev 'sort(all(), "topo")'
+  > EOF
+
+Setup
+-----
+
+create a repo with one root
+
+  $ hg init server
+  $ cd server
+  $ echo root > root
+  $ hg ci -Am "C-ROOT"
+  adding root
+  $ cd ..
+
+clone it in two clients
+
+  $ hg clone ssh://user@dummy/server client-racy
+  requesting all changes
+  adding changesets
+  adding manifests
+  adding file changes
+  added 1 changesets with 1 changes to 1 files
+  updating to branch default
+  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  $ hg clone ssh://user@dummy/server client-other
+  requesting all changes
+  adding changesets
+  adding manifests
+  adding file changes
+  added 1 changesets with 1 changes to 1 files
+  updating to branch default
+  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+
+setup one to allow race on push
+
+  $ cat >> client-racy/.hg/hgrc << EOF
+  > [extensions]
+  > delaypush = $TESTTMP/delaypush.py
+  > [delaypush]
+  > ready-path = $TESTTMP/readyfile
+  > release-path = $TESTTMP/watchfile
+  > EOF
+
+Simple race, both try to push to the server at the same time
+------------------------------------------------------------
+
+Both try to replace the same head
+
+#  a
+#  | b
+#  |/
+#  *
+
+Creating changesets
+
+  $ echo b > client-other/a
+  $ hg -R client-other/ add client-other/a
+  $ hg -R client-other/ commit -m "C-A"
+  $ echo b > client-racy/b
+  $ hg -R client-racy/ add client-racy/b
+  $ hg -R client-racy/ commit -m "C-B"
+
+Pushing
+
+  $ hg -R client-racy push -r 'tip' > ./push-log 2>&1 &
+
+  $ waiton $TESTTMP/readyfile
+
+  $ hg -R client-other push -r 'tip'
+  pushing to ssh://user@dummy/server
+  searching for changes
+  remote: adding changesets
+  remote: adding manifests
+  remote: adding file changes
+  remote: added 1 changesets with 1 changes to 1 files
+
+  $ release $TESTTMP/watchfile
+
+Check the result of the push
+
+  $ cat ./push-log
+  pushing to ssh://user@dummy/server
+  searching for changes
+  wrote ready: $TESTTMP/readyfile
+  waiting on: $TESTTMP/watchfile
+  abort: push failed:
+  'repository changed while pushing - please try again'
+
+  $ hg -R server graph
+  o  98217d5a1659 C-A (default)
+  |
+  @  842e2fac6304 C-ROOT (default)
+