--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/tests/test-hooklib-reject_merge_commits.t	Sat Sep 07 14:50:39 2019 +0200
@@ -0,0 +1,78 @@
+  $ cat <<EOF >> $HGRCPATH
+  > [extensions]
+  > hooklib =
+  > 
+  > [phases]
+  > publish = False
+  > EOF
+  $ hg init a
+  $ hg --cwd a debugbuilddag '.:parent.:childa*parent/childa<parent@otherbranch./childa'
+  $ hg --cwd a log -G
+  o    changeset:   4:a9fb040caedd
+  |\   branch:      otherbranch
+  | |  tag:         tip
+  | |  parent:      3:af739dfc49b4
+  | |  parent:      1:66f7d451a68b
+  | |  user:        debugbuilddag
+  | |  date:        Thu Jan 01 00:00:04 1970 +0000
+  | |  summary:     r4
+  | |
+  | o  changeset:   3:af739dfc49b4
+  | |  branch:      otherbranch
+  | |  parent:      0:1ea73414a91b
+  | |  user:        debugbuilddag
+  | |  date:        Thu Jan 01 00:00:03 1970 +0000
+  | |  summary:     r3
+  | |
+  +---o  changeset:   2:a6b287721c3b
+  | |/   parent:      0:1ea73414a91b
+  | |    parent:      1:66f7d451a68b
+  | |    user:        debugbuilddag
+  | |    date:        Thu Jan 01 00:00:02 1970 +0000
+  | |    summary:     r2
+  | |
+  o |  changeset:   1:66f7d451a68b
+  |/   tag:         childa
+  |    user:        debugbuilddag
+  |    date:        Thu Jan 01 00:00:01 1970 +0000
+  |    summary:     r1
+  |
+  o  changeset:   0:1ea73414a91b
+     tag:         parent
+     user:        debugbuilddag
+     date:        Thu Jan 01 00:00:00 1970 +0000
+     summary:     r0
+  
+  $ hg init b
+  $ cat <<EOF >> b/.hg/hgrc
+  > [hooks]
+  > pretxnchangegroup.reject_merge_commits = \
+  >   python:hgext.hooklib.reject_merge_commits.hook
+  > EOF
+  $ hg --cwd b pull ../a -r a6b287721c3b
+  pulling from ../a
+  adding changesets
+  adding manifests
+  adding file changes
+  error: pretxnchangegroup.reject_merge_commits hook failed: a6b287721c3b rejected as merge on the same branch. Please consider rebase.
+  transaction abort!
+  rollback completed
+  abort: a6b287721c3b rejected as merge on the same branch. Please consider rebase.
+  [255]
+  $ hg --cwd b pull ../a -r 1ea73414a91b
+  pulling from ../a
+  adding changesets
+  adding manifests
+  adding file changes
+  added 1 changesets with 0 changes to 0 files
+  new changesets 1ea73414a91b (1 drafts)
+  (run 'hg update' to get a working copy)
+  $ hg --cwd b pull ../a -r a9fb040caedd
+  pulling from ../a
+  searching for changes
+  adding changesets
+  adding manifests
+  adding file changes
+  added 3 changesets with 0 changes to 0 files
+  new changesets 66f7d451a68b:a9fb040caedd (3 drafts)
+  (run 'hg update' to get a working copy)