tests/test-rank.t

narrow: delegate the dirstate's narrow spec writing to the transaction

This make it more transactional and will help us to simplify their backup.

The implementation is not great, but it keep the patch simple as this is not the
time for a larger refactoring yet.

=============================================================
Check that we can compute and exchange revision rank properly
=============================================================

  $ cat << EOF >> $HGRCPATH
  > [format]
  > exp-use-changelog-v2=enable-unstable-format-and-corrupt-my-data
  > EOF


Test minimal rank computation with merge

  $ hg init rank-repo-minimal
  $ cd rank-repo-minimal
  $ touch 0
  $ hg commit -Aqm 0
  $ touch 1
  $ hg commit -Aqm 1
  $ hg update -qr 0
  $ touch 2
  $ hg commit -Aqm 2
  $ hg merge -qr 1
  $ hg commit -m 3
  $ touch 4
  $ hg commit -Aqm 4
  $ hg log --graph --template '{rev} {_fast_rank}\n'
  @  4 5
  |
  o    3 4
  |\
  | o  2 2
  | |
  o |  1 2
  |/
  o  0 1
  
  $ cd ..


Build a bigger example repo

  $ hg init rank-repo-generated
  $ cd rank-repo-generated
  $ hg debugbuilddag '.:root1+5:mp1<root1+10:mp2/mp1+3<mp1+2:mp3/mp2$+15/mp1+4'
  $ hg log -G -T '{desc}'
  o  r42
  |
  o  r41
  |
  o  r40
  |
  o  r39
  |
  o    r38
  |\
  | o  r37
  | |
  | o  r36
  | |
  | o  r35
  | |
  | o  r34
  | |
  | o  r33
  | |
  | o  r32
  | |
  | o  r31
  | |
  | o  r30
  | |
  | o  r29
  | |
  | o  r28
  | |
  | o  r27
  | |
  | o  r26
  | |
  | o  r25
  | |
  | o  r24
  | |
  | o  r23
  |
  | o    r22
  | |\
  | | o  r21
  | | |
  +---o  r20
  | |
  | | o  r19
  | | |
  | | o  r18
  | | |
  | | o  r17
  | | |
  +---o  r16
  | |/
  | o  r15
  | |
  | o  r14
  | |
  | o  r13
  | |
  | o  r12
  | |
  | o  r11
  | |
  | o  r10
  | |
  | o  r9
  | |
  | o  r8
  | |
  | o  r7
  | |
  | o  r6
  | |
  o |  r5
  | |
  o |  r4
  | |
  o |  r3
  | |
  o |  r2
  | |
  o |  r1
  |/
  o  r0
  


Check the rank
--------------

  $ hg log -G -T '{_fast_rank}'
  o  26
  |
  o  25
  |
  o  24
  |
  o  23
  |
  o    22
  |\
  | o  15
  | |
  | o  14
  | |
  | o  13
  | |
  | o  12
  | |
  | o  11
  | |
  | o  10
  | |
  | o  9
  | |
  | o  8
  | |
  | o  7
  | |
  | o  6
  | |
  | o  5
  | |
  | o  4
  | |
  | o  3
  | |
  | o  2
  | |
  | o  1
  |
  | o    19
  | |\
  | | o  8
  | | |
  +---o  7
  | |
  | | o  20
  | | |
  | | o  19
  | | |
  | | o  18
  | | |
  +---o  17
  | |/
  | o  11
  | |
  | o  10
  | |
  | o  9
  | |
  | o  8
  | |
  | o  7
  | |
  | o  6
  | |
  | o  5
  | |
  | o  4
  | |
  | o  3
  | |
  | o  2
  | |
  o |  6
  | |
  o |  5
  | |
  o |  4
  | |
  o |  3
  | |
  o |  2
  |/
  o  1