tests/test-exchange-obsmarkers-case-A7.t

graft: start using the cmdstate class to read and write data to graftstate

This patch replaces the logic to read and write data to graftstate file to use
the state.cmdstate() class.

The previous graftstate format didn't had any version number on top of that, so
we have to catch the CorruptedState error and then read the graftstate in case
of old state files.

This will help us to implement nice additions to graft commands like
`--no-commit`, `--abort`, `--stop` flags.

Passing on test-graft.t shows that things are working fine.

Differential Revision: https://phab.mercurial-scm.org/D3654

============================================
Testing obsolescence markers push: Cases A.7
============================================

Mercurial pushes obsolescences markers relevant to the "pushed-set", the set of
all changesets that requested to be "in sync" after the push (even if they are
already on both side).

This test belongs to a series of tests checking such set is properly computed
and applied. This does not tests "obsmarkers" discovery capabilities.

Category A: simple cases
TestCase 7: markers one non targeted common changeset

A.7 non targeted common changeset
=================================

.. {{{
..    ⇠◕ A
..     |
..     ● O
.. }}}
..
.. Markers exist from:
..
..  * Chain from A
..
.. Command run:
..
..  * hg push -r O
..
.. Expected exchange:
..
..  * ø

Setup
-----

  $ . $TESTDIR/testlib/exchange-obsmarker-util.sh

Initial

  $ setuprepos A.7
  creating test repo for test case A.7
  - pulldest
  - main
  - pushdest
  cd into `main` and proceed with env setup
  $ cd main
  $ mkcommit A
  $ hg push -q ../pushdest
  $ hg push -q ../pulldest
  $ hg debugobsolete aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa `getid 'desc(A)'`
  $ hg log -G --hidden
  @  f5bc6836db60 (draft): A
  |
  o  a9bdc8b26820 (public): O
  
  $ inspect_obsmarkers
  obsstore content
  ================
  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa f5bc6836db60e308a17ba08bf050154ba9c4fad7 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  $ cd ..
  $ cd ..

Actual Test
-----------------------------------

  $ dotest A.7 O
  ## Running testcase A.7
  # testing echange of "O" (a9bdc8b26820)
  ## initial state
  # obstore: main
  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa f5bc6836db60e308a17ba08bf050154ba9c4fad7 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  # obstore: pushdest
  # obstore: pulldest
  ## pushing "O" from main to pushdest
  pushing to pushdest
  searching for changes
  no changes found
  ## post push state
  # obstore: main
  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa f5bc6836db60e308a17ba08bf050154ba9c4fad7 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  # obstore: pushdest
  # obstore: pulldest
  ## pulling "a9bdc8b26820" from main into pulldest
  pulling from main
  no changes found
  ## post pull state
  # obstore: main
  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa f5bc6836db60e308a17ba08bf050154ba9c4fad7 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  # obstore: pushdest
  # obstore: pulldest