tests/test-push-checkheads-pruned-B2.t

merge: cache unknown dir checks (issue5716)

As mentioned in D1222, the recent pathconflicts change regresses update
performance in large repositories when many files are being updated.

To mitigate this, we introduce two caches of directories that have
already found to be either:

  - unknown directories, but which are not aliased by files and
    so don't need to be checked if they are files again; and

  - missing directores, which cannot cause path conflicts, and
    cannot contain a file that causes a path conflict.

When checking the paths of a file, testing against this caches means we can
skip tests that involve touching the filesystem.

Differential Revision: https://phab.mercurial-scm.org/D1224

====================================
Testing head checking code: Case B-2
====================================

Mercurial checks for the introduction of new heads on push. Evolution comes
into play to detect if existing branches on the server are being replaced by
some of the new one we push.

This case is part of a series of tests checking this behavior.

Category B: simple case involving pruned changesets
TestCase 2: multi-changeset branch, head is pruned, rest is superceeded

.. old-state:
..
.. * 2 changeset branch
..
.. new-state:
..
.. * old head is pruned
.. * 1 new branch succeeding to the other changeset in the old branch
..
.. expected-result:
..
.. * push allowed
..
.. graph-summary:
..
..   B ⊗
..     |
..   A ø⇠◔ A'
..     |/
..     ●

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

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

  $ mkdir B2
  $ cd B2
  $ setuprepos
  creating basic server and client repo
  updating to branch default
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd server
  $ mkcommit B0
  $ cd ../client
  $ hg pull
  pulling from $TESTTMP/B2/server (glob)
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files
  new changesets d73caddc5533
  (run 'hg update' to get a working copy)
  $ hg up 0
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ mkcommit A1
  created new head
  $ hg debugobsolete `getid "desc(A0)" ` `getid "desc(A1)"`
  obsoleted 1 changesets
  $ hg debugobsolete --record-parents `getid "desc(B0)"`
  obsoleted 1 changesets
  $ hg log -G --hidden
  @  f6082bc4ffef (draft): A1
  |
  | x  d73caddc5533 (draft): B0
  | |
  | x  8aaa48160adc (draft): A0
  |/
  o  1e4be0697311 (public): root
  

Actual testing
--------------

  $ hg push
  pushing to $TESTTMP/B2/server (glob)
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files (+1 heads)
  2 new obsolescence markers
  obsoleted 2 changesets

  $ cd ../..