view tests/test-single-head-obsolescence-named-branch-A2.t @ 50195:11e6eee4b063

transaction: use the standard transaction mechanism to backup branch

Branch is a bit special :
- It currently does not collaborate with the transaction (or any scoping) for
  writing (this is bad)
- It can change without the lock being taken (it is protected by `wlock`)

So we rely on the same mechanism as for the backup of the other dirstate file:
- we only do a backup if we hold the wlock
- we force a backup though the transaction


Since "branch" write does not collaborate with the transaction, we cannot back
it up "at the last minute" as we do for the dirstate. We have to back it up
"upfront". Since we have a backup, the transaction is no longer doing its
"quick_abort" and get noisy. Which is quite annoying. To work around this, and
to avoid jumping in yet-another-rabbit-hole of "getting branch written
properly", I am doing horrible things to the transaction in the meantime.
We should be able to get this code go away during the next cycle.

In the meantime, I prefer to take this small stop so that we stop abusing the
"journal" and "undo" mechanism instead of the proper backup mechanism of the
transaction.


Also note that this change regress the warning message for the legacy fallback
introduced in 2008 when issue902 got fixed in dd5a501cb97f (Mercurial 1.0).

I feel like this is fine as issue 902 remains fixed, and this would only affect
people deploying a mix of 15 year old Mercurial and modern mercurial, and using
branch and rollback extensively.

=========================================
Testing single head enforcement: Case A-2
=========================================

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 2: A branch is split in two, effectively creating two heads

.. old-state:
..
.. * 2 changesets on branch default
.. * 2 changesets on branch Z on top of them
..
.. new-state:
..
.. * 2 changesets on branch Z at the same location
.. * 1 changeset on branch default unchanged
.. * 1 changeset on branch default superseding the other ones
..
.. expected-result:
..
.. * two heads detected
..
.. graph-summary:
..
..   D ●      (branch Z)
..     |
..   C ●      (branch Z)
..     |
..   B ø⇠◔ B'
..     | |
..   A ● |
..     |/
..     ●

  $ . $TESTDIR/testlib/push-checkheads-util.sh

  $ cat >> $HGRCPATH << EOF
  > [command-templates]
  > log = "{node|short} [{branch}] ({phase}): {desc}\n"
  > EOF

Test setup
----------

  $ mkdir A2
  $ cd A2
  $ 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
  $ mkcommit B0
  $ hg branch Z
  marked working directory as branch Z
  (branches are permanent and global, did you want a bookmark?)
  $ mkcommit C0
  $ mkcommit D0
  $ hg push --new-branch
  pushing to $TESTTMP/A2/server
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 3 changesets with 3 changes to 3 files
  $ hg up 0
  0 files updated, 0 files merged, 4 files removed, 0 files unresolved
  $ mkcommit B1
  created new head
  $ hg debugobsolete `getid "desc(B0)"` `getid "desc(B1)"`
  1 new obsolescence markers
  obsoleted 1 changesets
  2 new orphan changesets
  $ hg heads
  25c56d33e4c4 [default] (draft): B1
  cdf1dbb37a67 [Z] (draft): D0
  8aaa48160adc [default] (draft): A0
  $ hg log -G --hidden
  @  25c56d33e4c4 [default] (draft): B1
  |
  | *  cdf1dbb37a67 [Z] (draft): D0
  | |
  | *  3213e3e16c67 [Z] (draft): C0
  | |
  | x  d73caddc5533 [default] (draft): B0
  | |
  | o  8aaa48160adc [default] (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("B1")' --force
  pushing to $TESTTMP/A2/server
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  transaction abort!
  rollback completed
  abort: rejecting multiple heads on branch "default"
  (2 heads: 8aaa48160adc 25c56d33e4c4)
  [255]