view tests/test-diff-hashes.t @ 45121:b6269741ed42

config: add option to control creation of empty successors during rewrite

The default for many history-rewriting commands (e.g. rebase and absorb) is
that changesets which would become empty are not created in the target branch.
This makes sense if the source branch consists of small fix-up changes. For
more advanced workflows that make heavy use of history-editing to create
curated patch series, dropping empty changesets is not as important or even
undesirable.

Some users want to keep the meta-history, e.g. to make finding comments in a
code review tool easier or to avoid that divergent bookmarks are created. For
that, obsmarkers from the (to-be) empty changeset to the changeset(s) that
already made the changes should be added. If a to-be empty changeset is pruned
without a successor, adding the obsmarkers is hard because the changeset has to
be found within the hidden part of the history.

If rebasing in TortoiseHg, it’s easy to miss the fact that the to-be empty
changeset was pruned. An empty changeset will function as a reminder that
obsmarkers should be added.

Martin von Zweigbergk mentioned another advantage. Stripping the successor will
de-obsolete the predecessor. If no (empty) successor is created, this won’t be
possible.

In the future, we may want to consider other behaviors, like e.g. creating the
empty successor, but pruning it right away. Therefore this configuration
accepts 'skip' and 'keep' instead of being a boolean configuration.

  $ hg init a
  $ cd a

  $ hg diff inexistent1 inexistent2
  inexistent1: * (glob)
  inexistent2: * (glob)

  $ echo bar > foo
  $ hg add foo
  $ hg ci -m 'add foo'

  $ echo foobar > foo
  $ hg ci -m 'change foo'

  $ hg --quiet diff -r 0 -r 1
  diff -r a99fb63adac3 -r 9b8568d3af2f foo
  --- a/foo	Thu Jan 01 00:00:00 1970 +0000
  +++ b/foo	Thu Jan 01 00:00:00 1970 +0000
  @@ -1,1 +1,1 @@
  -bar
  +foobar

  $ hg diff -r 0 -r 1
  diff -r a99fb63adac3 -r 9b8568d3af2f foo
  --- a/foo	Thu Jan 01 00:00:00 1970 +0000
  +++ b/foo	Thu Jan 01 00:00:00 1970 +0000
  @@ -1,1 +1,1 @@
  -bar
  +foobar

  $ hg --verbose diff -r 0 -r 1
  diff -r a99fb63adac3 -r 9b8568d3af2f foo
  --- a/foo	Thu Jan 01 00:00:00 1970 +0000
  +++ b/foo	Thu Jan 01 00:00:00 1970 +0000
  @@ -1,1 +1,1 @@
  -bar
  +foobar

  $ hg --debug diff -r 0 -r 1
  diff -r a99fb63adac3f31816a22f665bc3b7a7655b30f4 -r 9b8568d3af2f1749445eef03aede868a6f39f210 foo
  --- a/foo	Thu Jan 01 00:00:00 1970 +0000
  +++ b/foo	Thu Jan 01 00:00:00 1970 +0000
  @@ -1,1 +1,1 @@
  -bar
  +foobar

  $ cd ..