tests/test-rank.t

transaction: quietly rollback if no other changes than temporary files

If no actual change have been made, we don't really need to roll them back. We
only have to cleanup some temporary files and it seems reasonable to do that
quietly.

This will help us to use the transaction in wider context¹ without impacting the
user experience.

[1] as in Python context managers that lives longer.

=============================================================
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