--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/tests/test-single-head-obsolescence-topic-B5.t	Thu Mar 12 02:08:39 2020 +0100
@@ -0,0 +1,117 @@
+=========================================
+Testing single head enforcement: Case A-1
+=========================================
+
+A repository is set to only accept a single head per name (typically named
+branch). However, obsolete changesets can make this enforcement more
+complicated, because they can be kept visible by other changeset on other
+branch.
+
+This case is part of a series of tests checking this behavior.
+
+Category A: Involving obsolescence
+TestCase 1: obsoleting a merge reveal two heads
+
+.. old-state:
+..
+.. * 3 changeset changeset on topic X (2 on their own branch + 1 merge)
+.. * 1 changeset on topic Y (children of the merge)
+..
+.. new-state:
+..
+.. * 2 changeset changeset on topic X (merge is obsolete) each a head
+.. * 1 changeset on topic Y keeping the merge visible
+..
+.. expected-result:
+..
+.. * 2 heads detected (because we skip the merge).
+..
+.. graph-summary:
+..
+..   D ●      (topic-Y)
+..     |
+..   C ●      (topic-Y)
+..     |
+..   M ⊗      (topic-X)
+..     |\
+..   A ● ● B  (topic-X)
+..     |/
+..     ●
+
+  $ . $TESTDIR/testlib/topic_setup.sh
+  $ . $TESTDIR/testlib/push-checkheads-util.sh
+
+Test setup
+----------
+
+  $ mkdir B5
+  $ cd B5
+  $ setuprepos single-head
+  creating basic server and client repo
+  updating to branch default
+  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  $ cd client
+  $ hg topic -r . topic-X
+  switching to topic topic-X
+  changed topic on 1 changesets to "topic-X"
+  $ hg strip --config extensions.strip= --hidden 'hidden()' --no-backup # clean old A0
+  $ hg up 0
+  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
+  $ hg topic topic-X
+  marked working directory as topic: topic-X
+  $ mkcommit B0
+  $ hg merge
+  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  (branch merge, don't forget to commit)
+  $ hg ci -m 'M0'
+  $ hg topic topic-Y
+  $ mkcommit C0
+  active topic 'topic-Y' grew its first changeset
+  (see 'hg help topics' for more information)
+  $ hg push --new-branch
+  pushing to $TESTTMP/B5/server
+  searching for changes
+  adding changesets
+  adding manifests
+  adding file changes
+  added 4 changesets with 2 changes to 3 files (+1 heads)
+  1 new obsolescence markers
+  obsoleted 1 changesets
+  $ hg up 0
+  0 files updated, 0 files merged, 3 files removed, 0 files unresolved
+  $ mkcommit A1
+  $ mkcommit B1
+  $ hg debugobsolete `getid "desc(M0)"` --record-parents
+  1 new obsolescence markers
+  obsoleted 1 changesets
+  1 new orphan changesets
+  $ hg log -G --hidden
+  @  262c8c798096 [default] (draft): B1
+  |
+  o  f6082bc4ffef [default] (draft): A1
+  |
+  | *  339fd31549ed [default:topic-Y] (draft): C0
+  | |
+  | x    33b3d4185449 [default:topic-X] (draft): M0
+  | |\
+  +---o  d3826ff42cf7 [default:topic-X] (draft): B0
+  | |
+  | o  5a47a98cd8e5 [default:topic-X] (draft): A0
+  |/
+  o  1e4be0697311 [default] (public): root
+  
+
+Actual testing
+--------------
+
+(force push to make sure we get the changeset on the remote)
+
+  $ hg push -r 'desc("C0")' --force
+  pushing to $TESTTMP/B5/server
+  searching for changes
+  no changes found
+  transaction abort!
+  rollback completed
+  abort: rejecting multiple heads on branch "default:topic-X"
+  (2 heads: 5a47a98cd8e5 d3826ff42cf7)
+  [255]