tests/test-exchange-obsmarkers-case-B7.t

nodemap: add a (python) index class for persistent nodemap testing

Using the persistent nodemap require a compeling performance boost and an
existing implementation. The benefit of the persistent nodemap for pure python
code is unclear and we don't have a C implementation for it. Yet we would like
to actually start testing it in more details and define an API for using that
persistent nodemap.

We introduce a new `devel` config option to use an index class dedicated to
Nodemap Testing. This feature is "pure" only because having using a pure-python
index with the `cext` policy proved more difficult than I would like.

There is nothing going on in that class for now, but the coming changeset will
change that.

Differential Revision: https://phab.mercurial-scm.org/D7840

============================================
Testing obsolescence markers push: Cases B.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 B: pruning case
TestCase 7: Prune on non-targeted common changeset

B.7 Prune above non-targeted common changeset
=============================================

.. (very similar to B1, but the prune changeset is unknown on remote)
..
.. {{{
..     ⊗ B
..     |
..     ◕ A
..     |
..     ● O
.. }}}
..
.. Marker exist from:
..
..  * B (prune)
..
.. Command runs:
..
..  * hg push -r O
..
.. Expected exclude:
..
..  * B (prune)

Setup
-----

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

Initial

  $ setuprepos B.7
  creating test repo for test case B.7
  - pulldest
  - main
  - pushdest
  cd into `main` and proceed with env setup
  $ cd main
  $ mkcommit A
  $ hg push -q ../pushdest
  $ hg push -q ../pulldest
  $ mkcommit B
  $ hg prune -qd '0 0' .
  $ hg log -G --hidden
  x  f6fbb35d8ac9 (draft): B
  |
  @  f5bc6836db60 (draft): A
  |
  o  a9bdc8b26820 (public): O
  
  $ inspect_obsmarkers
  obsstore content
  ================
  f6fbb35d8ac958bbe70035e4c789c18471cdc0af 0 {f5bc6836db60e308a17ba08bf050154ba9c4fad7} (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  $ cd ..
  $ cd ..

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

  $ dotest B.7 O
  ## Running testcase B.7
  # testing echange of "O" (a9bdc8b26820)
  ## initial state
  # obstore: main
  f6fbb35d8ac958bbe70035e4c789c18471cdc0af 0 {f5bc6836db60e308a17ba08bf050154ba9c4fad7} (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
  f6fbb35d8ac958bbe70035e4c789c18471cdc0af 0 {f5bc6836db60e308a17ba08bf050154ba9c4fad7} (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
  f6fbb35d8ac958bbe70035e4c789c18471cdc0af 0 {f5bc6836db60e308a17ba08bf050154ba9c4fad7} (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  # obstore: pushdest
  # obstore: pulldest