tests/test-push-checkheads-partial-C4.t

log: add -L/--line-range option to follow file history by line range

We add an experimental -L/--line-range option to 'hg log' taking file patterns
along with a line range using the (new) FILE,FROMLINE-TOLINE syntax where FILE
may be a pattern (matching exactly one file). The resulting history is similar
to what the "followlines" revset except that, if --patch is specified,
only diff hunks within specified line range are shown.

Basically, this brings the CLI on par with what currently only exists in hgweb
through line selection in "file" and "annotate" views resulting in a file log
with filtered patch to only display followed line range.

The option may be specified multiple times and can be combined with --rev and
regular file patterns to further restrict revisions. Usage of this option
requires --follow; revisions are shown in descending order and renames are
followed. Only the --graph option is currently not supported.

The UI is the result of a consensus from review feedback at:

  https://www.mercurial-scm.org/pipermail/mercurial-devel/2017-October/106749.html


The implementation spreads between commands.log() and cmdutil module.
In commands.log(), the main loop may now use a "hunksfilter" factory (similar
to "filematcher") that, for a given "rev", produces a filtering function
for diff hunks for a given file context object.
The logic to build revisions from -L/--line-range options lives in
cmdutil.getloglinerangerevs() which produces "revs", "filematcher" and
"hunksfilter" information. Revisions obtained by following files' line range
are filtered if they do not match the revset specified by --rev option. If
regular FILE arguments are passed along with -L options, both filematchers are
combined into a new matcher.

.. feature::

   Add an experimental -L/--line-range FILE,FROMLINE-TOLINE option to 'hg log'
   command to follow the history of files by line range. In combination with
   -p/--patch option, only diff hunks within specified line range will be
   displayed. Feedback, especially on UX aspects, is welcome.

====================================
Testing head checking code: Case C-4
====================================

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 C: case were the branch is only partially obsoleted
TestCase 4: 2 changeset branch, only the base is pruned

.. old-state:
..
.. * 2 changeset branch
..
.. new-state:
..
.. * old base is pruned
.. * 1 new unrelated branch
..
.. expected-result:
..
.. * push denied
..
.. graph-summary:
..
..   B ◔
..     |
..   A ⊗ ◔ C
..     |/
..     ●

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

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

  $ mkdir C4
  $ cd C4
  $ 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/C4/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 C0
  created new head
  $ hg debugobsolete --record-parents `getid "desc(A0)"`
  obsoleted 1 changesets
  $ hg log -G --hidden
  @  0f88766e02d6 (draft): C0
  |
  | o  d73caddc5533 (draft): B0
  | |
  | x  8aaa48160adc (draft): A0
  |/
  o  1e4be0697311 (public): root
  

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

  $ hg push --rev 'desc(C0)'
  pushing to $TESTTMP/C4/server (glob)
  searching for changes
  abort: push creates new remote head 0f88766e02d6!
  (merge or see 'hg help push' for details about pushing new heads)
  [255]

  $ cd ../..