tests/test-push-checkheads-unpushed-D4.t

diff: also yield file context objects in patch.trydiff() (API)

And retrieve them in patch.diffhunks(). We'll use these in forthcoming
changesets to filter diff hunks by line range.

====================================
Testing head checking code: Case D-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 D: remote head is "obs-affected" locally, but result is not part of the push
TestCase 4: multi-changeset branch, split on multiple other, (base on its own new branch)

.. old-state:
..
.. * 2 branch (1 changeset, and 2 changesets)
..
.. new-state:
..
.. * 1 new branch superceeding the base of the old-2-changesets-branch,
.. * 1 new changesets on the old-1-changeset-branch superceeding the head of the other
..
.. expected-result:
..
.. * push the new branch only -> push denied (variant a)
.. * push the existing branch only -> push allowed (variant b)
.. (pushing all is tested as case A-7)
..
.. graph-summary:
..
.. (variant a)
..
.. B'○⇢ø B
..   | |
.. A | ø⇠◔ A'
..   | |/
.. C ● |
..    \|
..     ●
..
.. or (variant b)
..
.. B'◔⇢ø B
..   | |
.. A | ø⇠○ A'
..   | |/
.. C ● |
..    \|
..     ●

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

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

  $ mkdir D4
  $ cd D4
  $ 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
  $ hg up 0
  0 files updated, 0 files merged, 2 files removed, 0 files unresolved
  $ mkcommit C0
  created new head
  $ cd ../client
  $ hg pull
  pulling from $TESTTMP/D4/server (glob)
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 2 changesets with 2 changes to 2 files (+1 heads)
  new changesets d73caddc5533:0f88766e02d6
  (run 'hg heads' to see heads, 'hg merge' to merge)
  $ hg up 0
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ mkcommit A1
  created new head
  $ hg up 'desc(C0)'
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ mkcommit B1
  $ hg debugobsolete `getid "desc(A0)" ` `getid "desc(A1)"`
  obsoleted 1 changesets
  $ hg debugobsolete `getid "desc(B0)" ` `getid "desc(B1)"`
  obsoleted 1 changesets
  $ hg log -G --hidden
  @  d70a1f75a020 (draft): B1
  |
  | o  f6082bc4ffef (draft): A1
  | |
  o |  0f88766e02d6 (draft): C0
  |/
  | x  d73caddc5533 (draft): B0
  | |
  | x  8aaa48160adc (draft): A0
  |/
  o  1e4be0697311 (public): root
  

Actual testing (new branch only)
--------------------------------

  $ hg push --rev 'desc(A1)'
  pushing to $TESTTMP/D4/server (glob)
  searching for changes
  abort: push creates new remote head f6082bc4ffef!
  (merge or see 'hg help push' for details about pushing new heads)
  [255]

Actual testing (existing branch only)
------------------------------------

  $ hg push --rev 'desc(B1)'
  pushing to $TESTTMP/D4/server (glob)
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files
  1 new obsolescence markers
  obsoleted 1 changesets

  $ cd ../..