tests/test-basic.t

checkheads: upgrade the obsolescence postprocessing logic (issue4354)

The previous logic had many shortcoming (eg: looking at the head only, not
handling prune, etc...), the new logic use a more robust approach:

For each head, we check if after the push all changesets exclusive to this heads
will be obsolete. If they are, the branch considered be "replaced".

To check if a changeset will be obsolete, we simply checks:

* the changeset phase

* the existence of a marker relevant to the "pushed set" that affects the
  changesets..

This fixes two major issues of the previous algorithm:

* branch partially rewritten (eg: head but not root) are no longer detected as
  replaced,

* Prune are now properly handled.

(This implementation was introduction in the evolve extension, version 6.0.0.)

This new algorithm has an extended number of tests, a basic one is provided
in this patch. The others will be introduced in their own changeset for clarity.

In addition, we stop trying to process heads unknown locally, we do not have
enough data to take an informed decision so we should stop pretending we do.
This reflect a test that is now update.

Create a repository:

  $ hg config
  defaults.backout=-d "0 0"
  defaults.commit=-d "0 0"
  defaults.shelve=--date "0 0"
  defaults.tag=-d "0 0"
  devel.all-warnings=true
  largefiles.usercache=$TESTTMP/.cache/largefiles (glob)
  ui.slash=True
  ui.interactive=False
  ui.mergemarkers=detailed
  ui.promptecho=True
  web.address=localhost
  web\.ipv6=(?:True|False) (re)
  $ hg init t
  $ cd t

Prepare a changeset:

  $ echo a > a
  $ hg add a

  $ hg status
  A a

Writes to stdio succeed and fail appropriately

#if devfull
  $ hg status 2>/dev/full
  A a

  $ hg status >/dev/full
  abort: No space left on device
  [255]

  $ hg status >/dev/full 2>&1
  [1]

  $ hg status ENOENT 2>/dev/full
  [1]
#endif

  $ hg commit -m test

This command is ancient:

  $ hg history
  changeset:   0:acb14030fe0a
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     test
  

Verify that updating to revision 0 via commands.update() works properly

  $ cat <<EOF > update_to_rev0.py
  > from mercurial import ui, hg, commands
  > myui = ui.ui.load()
  > repo = hg.repository(myui, path='.')
  > commands.update(myui, repo, rev=0)
  > EOF
  $ hg up null
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ python ./update_to_rev0.py
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg identify -n
  0


Poke around at hashes:

  $ hg manifest --debug
  b789fdd96dc2f3bd229c1dd8eedf0fc60e2b68e3 644   a

  $ hg cat a
  a

Verify should succeed:

  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  1 files, 1 changesets, 1 total revisions

At the end...

  $ cd ..