view tests/test-issue2137.t @ 26228:0fd20a71abdb

extdiff: add a --patch argument for diffing changeset deltas

One of the things I missed the most when transitioning from versioned MQ to
evolve was the loss of being able to check that rebase conflicts were properly
resolved by:

  $ hg ci --mq -m "before"
  $ hg rebase -s qbase -d tip
  $ hg bcompare --mq

The old csets stay in the tree with evolve, but a straight diff includes all of
the other changes that were pulled in, obscuring the code that was rebased.
Diffing deltas can be confusing, but unless radical changes were made during the
resolve, it is very clear when individual hunks are added, dropped or modified.
Unlike the MQ technique, this can only compare a single pair of csets/patches at
a time.  Like the MQ method, this also highlights changes in the commit comment
and other metadata.

I originally tried monkey patching from the evolve extension, but that is too
complicated given that it depends on the order the two different extensions are
loaded.  This functionality is also useful when comparing grafts however, so
implementing it in the core is more than just convenience.

The --change argument doesn't make much sense for this, but it isn't harmful so
I didn't bother blocking it.  The -I/-X options are ignored because of a
limitation of cmdutil.export().  We'll fix that next.

http://mercurial.selenic.com/bts/issue2137

Setup:

create a little extension that has 3 side-effects:
1) ensure changelog data is not inlined
2) make revlog to use lazyparser
3) test that repo.lookup() works
1 and 2 are preconditions for the bug; 3 is the bug.

  $ cat > commitwrapper.py <<EOF
  > from mercurial import extensions, node, revlog
  > 
  > def reposetup(ui, repo):
  >     class wraprepo(repo.__class__):
  >         def commit(self, *args, **kwargs):
  >             result = super(wraprepo, self).commit(*args, **kwargs)
  >             tip1 = node.short(repo.changelog.tip())
  >             tip2 = node.short(repo.lookup(tip1))
  >             assert tip1 == tip2
  >             ui.write('new tip: %s\n' % tip1)
  >             return result
  >     repo.__class__ = wraprepo
  > 
  > def extsetup(ui):
  >     revlog._maxinline = 8             # split out 00changelog.d early
  >     revlog._prereadsize = 8           # use revlog.lazyparser
  > EOF

  $ cat >> $HGRCPATH <<EOF
  > [extensions]
  > commitwrapper = `pwd`/commitwrapper.py
  > EOF

  $ hg init repo1
  $ cd repo1
  $ echo a > a
  $ hg commit -A -m'add a with a long commit message to make the changelog a bit bigger'
  adding a
  new tip: 553596fad57b

Test that new changesets are visible to repo.lookup():

  $ echo a >> a
  $ hg commit -m'one more commit to demonstrate the bug'
  new tip: 799ae3599e0e

  $ hg tip
  changeset:   1:799ae3599e0e
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     one more commit to demonstrate the bug
  

  $ cd ..