tests/test-absorb-edit-lines.t

loggingutil: add basic logger backends

These classes will be used in command server. They are similar to
the blackboxlogger, but it can't be factored out since the blackbox is so
tightly coupled with a repo object.

  $ cat >> $HGRCPATH << EOF
  > [extensions]
  > absorb=
  > EOF

  $ hg init repo1
  $ cd repo1

Make some commits:

  $ for i in 1 2 3; do
  >   echo $i >> a
  >   hg commit -A a -m "commit $i" -q
  > done

absorb --edit-lines will run the editor if filename is provided:

  $ hg absorb --edit-lines --apply-changes
  nothing applied
  [1]
  $ HGEDITOR=cat hg absorb --edit-lines --apply-changes a
  HG: editing a
  HG: "y" means the line to the right exists in the changeset to the top
  HG:
  HG: /---- 4ec16f85269a commit 1
  HG: |/--- 5c5f95224a50 commit 2
  HG: ||/-- 43f0a75bede7 commit 3
  HG: |||
      yyy : 1
       yy : 2
        y : 3
  nothing applied
  [1]

Edit the file using --edit-lines:

  $ cat > editortext << EOF
  >       y : a
  >      yy :  b
  >      y  : c
  >     yy  : d  
  >     y y : e
  >     y   : f
  >     yyy : g
  > EOF
  $ HGEDITOR='cat editortext >' hg absorb -q --edit-lines --apply-changes a
  $ hg cat -r 0 a
  d  
  e
  f
  g
  $ hg cat -r 1 a
   b
  c
  d  
  g
  $ hg cat -r 2 a
  a
   b
  e
  g