view tests/test-evolve-content-divergent-case-A4.t @ 5572:d7d954b6d518

evolve: remove swapping nodes logic while resolving divergence

Before this patch, while solving content-divergence if one of the
divergent cset need to relocate to resolution parent we used to set that
cset to "other" side; so it was like we are always going to relocate "other"
side which made us to swap the two if "divergent" cset need to relocate.

Above mentioned solution for relocating cset was not good and led us to incorrect
output in some cases.

So this patch, simplify the logic and remove the swapping thing and clearly depend
on resolution parent to check if any of the divergent cset needs to relocate.
This also means that now in some cases if both the divergent csets needs
to relocate, both will be relocated. Even before this patch, there are some cases
where both the divergent csets relocated but not in every case where it should
have.

Coming to the changes in test files:
1) changes in order of merging the two divergent csets is due to fact that
   now "divergent" and "other" are not swapped and hence "divergent" will be at
   local side and "other" will be at "other", which also results in change in
   the hash id for some cases.

2) extra changesets: which is the result of the fact that now we don't miss
   any case where both the divergent csets should be based on resolution parent
   before performing the merge -> which caught some cases and performed relocation,
   hence extra changesets. Although you can find that there is no changes in file
   content because of these relocation, but I remember loosing some data because
   of not relocating the "divergent", so why leave any risk out there by not
   relocating "other" to the resolution parent.

===============================================
Testing content-divergence resolution: Case A.4
===============================================

Independent rewrites of same changeset can lead to content-divergence. In most
common cases, it can occur when multiple users rewrite the same changeset
independently and push it.

This test belongs to a series of tests checking the resolution of content-divergent
changesets.

Category A: no parents are obsolete
Testcase 4: both sides relocated forward to different location but aligned
Variants:
# a: local is ahead of other
# b: other is ahead of local

A.4 Both relocated forward
==========================

.. (Divergence reason):
..    local: relocated the changeset forward in the graph but on the same topo branch
..    other: relocated the changeset forward in the graph but on the same topo branch
.. Where we show that since both changesets relocated forward in the graph,
.. we can assume the reason for ahead one being ahead is that it's rebased on the latest changes and
.. its parent should be the resolution parent. So, we will relocate the other changeset to resolution
.. parent and perform 3-way merge.
..
.. (local):
..
..    D ø⇠○ D'
..      | |
..      | ○ C
..      | |
..      | ○ B
..      \ |
..        ○ A
..        |
..        ● O
..
.. (other):
..
..    D ø⇠○ D''
..      | |  ○ C
..      | | /
..      | ○ B
..      \ |
..        ○ A
..        |
..        ● O
..
.. (Resolution):
..     ○ D'''
..     |
..     ○ C
..     |
..     ○ B
..     |
..     ○ A
..     |
..     ● O
..

Setup
-----
  $ . $TESTDIR/testlib/content-divergence-util.sh
  $ setuprepos A.4
  creating test repo for test case A.4
  - upstream
  - local
  - other
  cd into `local` and proceed with env setup

initial

  $ cd upstream
  $ mkcommit A
  $ mkcommit B
  $ mkcommit C
  $ hg co -r 'desc(A)'
  0 files updated, 0 files merged, 2 files removed, 0 files unresolved
  $ mkcommit D
  created new head
  $ cd ../local
  $ hg pull -qu
  $ hg rebase -r 'desc(D)' -d 'desc(C)'
  rebasing 4:6a418860e87b "D" (tip)

  $ cd ../other
  $ hg pull -qu
  $ hg rebase -r 'desc(D)' -d 'desc(B)'
  rebasing 4:6a418860e87b "D" (tip)
  $ hg push -q

  $ cd ../local
  $ hg push -q
  2 new content-divergent changesets
  $ hg pull -q
  2 new content-divergent changesets

Actual test of resolution
-------------------------

Variant_a: when local is ahead of other
---------------------------------------

  $ hg evolve -l
  d203ddccc9cc: D
    content-divergent: 5d3fd66cb347 (draft) (precursor 6a418860e87b)
  
  5d3fd66cb347: D
    content-divergent: d203ddccc9cc (draft) (precursor 6a418860e87b)
  
  $ hg log -G --hidden
  *  6:5d3fd66cb347 (draft): D [content-divergent]
  |
  | @  5:d203ddccc9cc (draft): D [content-divergent]
  | |
  | | x  4:6a418860e87b (draft): D
  | | |
  | o |  3:d90aa47aa5d3 (draft): C
  |/ /
  o /  2:f6fbb35d8ac9 (draft): B
  |/
  o  1:f5bc6836db60 (draft): A
  |
  o  0:a9bdc8b26820 (public): O
  
  $ hg evolve --content-divergent
  merge:[5] D
  with: [6] D
  base: [4] D
  rebasing "other" content-divergent changeset 5d3fd66cb347 on d90aa47aa5d3
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  working directory is now at 898f6bbfb21e

  $ hg log -G
  @  8:898f6bbfb21e (draft): D
  |
  o  3:d90aa47aa5d3 (draft): C
  |
  o  2:f6fbb35d8ac9 (draft): B
  |
  o  1:f5bc6836db60 (draft): A
  |
  o  0:a9bdc8b26820 (public): O
  
  $ hg evolve -l

Variant_b: when other is ahead of local
---------------------------------------

  $ cd ../other
  $ hg pull -q
  2 new content-divergent changesets

  $ hg evolve -l
  5d3fd66cb347: D
    content-divergent: d203ddccc9cc (draft) (precursor 6a418860e87b)
  
  d203ddccc9cc: D
    content-divergent: 5d3fd66cb347 (draft) (precursor 6a418860e87b)
  
  $ hg log -G --hidden
  *  6:d203ddccc9cc (draft): D [content-divergent]
  |
  | @  5:5d3fd66cb347 (draft): D [content-divergent]
  | |
  | | x  4:6a418860e87b (draft): D
  | | |
  o | |  3:d90aa47aa5d3 (draft): C
  |/ /
  o /  2:f6fbb35d8ac9 (draft): B
  |/
  o  1:f5bc6836db60 (draft): A
  |
  o  0:a9bdc8b26820 (public): O
  
  $ hg evolve --content-divergent
  merge:[5] D
  with: [6] D
  base: [4] D
  rebasing "divergent" content-divergent changeset 5d3fd66cb347 on d90aa47aa5d3
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  working directory is now at b2ef9cafa8ac

  $ hg log -G
  @  8:b2ef9cafa8ac (draft): D
  |
  o  3:d90aa47aa5d3 (draft): C
  |
  o  2:f6fbb35d8ac9 (draft): B
  |
  o  1:f5bc6836db60 (draft): A
  |
  o  0:a9bdc8b26820 (public): O