view tests/test-merge-default.t @ 18986:2f7186400a07

ancestor: a new algorithm that is faster for nodes near tip

Instead of walking all the way to the root of the DAG, we generate
a set of candidate GCA revs, then figure out which ones will win
the race to the root (usually without needing to traverse all the
way to the root).

In the common case of nodes that are close to each other in both
revision number and topology, this is usually a big win: it makes
"hg --time debugancestors" up to 9 times faster than the more general
ancestor function when measured on heads of the linux-2.6 hg repo.

Victory is not assured, however. The older function can still win
by a large margin if one node is much closer to the root than the
other, or by a much smaller amount if one is an ancestor of the
other.

For now, we've also got a small paranoid harness function that calls
both ancestor functions on every input and ensures that they give
equivalent answers.

Even without the checker function, the old ancestor function needs
to stay alive for the time being, as its generality is used by
context.filectx.merge.

  $ hg init
  $ echo a > a
  $ hg commit -A -ma
  adding a

  $ echo b >> a
  $ hg commit -mb

  $ echo c >> a
  $ hg commit -mc

  $ hg up 1
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ echo d >> a
  $ hg commit -md
  created new head

  $ hg up 1
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ echo e >> a
  $ hg commit -me
  created new head

  $ hg up 1
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

Should fail because not at a head:

  $ hg merge
  abort: branch 'default' has 3 heads - please merge with an explicit rev
  (run 'hg heads .' to see heads)
  [255]

  $ hg up
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

Should fail because > 2 heads:

  $ HGMERGE=internal:other; export HGMERGE
  $ hg merge
  abort: branch 'default' has 3 heads - please merge with an explicit rev
  (run 'hg heads .' to see heads)
  [255]

Should succeed:

  $ hg merge 2
  0 files updated, 1 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ hg commit -mm1

Should succeed - 2 heads:

  $ hg merge -P
  changeset:   3:ea9ff125ff88
  parent:      1:1846eede8b68
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     d
  
  $ hg merge
  0 files updated, 1 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ hg commit -mm2

Should fail because at tip:

  $ hg merge
  abort: nothing to merge
  [255]

  $ hg up 0
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

Should fail because there is only one head:

  $ hg merge
  abort: nothing to merge
  (use 'hg update' instead)
  [255]

  $ hg up 3
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ echo f >> a
  $ hg branch foobranch
  marked working directory as branch foobranch
  (branches are permanent and global, did you want a bookmark?)
  $ hg commit -mf

Should fail because merge with other branch:

  $ hg merge
  abort: branch 'foobranch' has one head - please merge with an explicit rev
  (run 'hg heads' to see all heads)
  [255]


Test for issue2043: ensure that 'merge -P' shows ancestors of 6 that
are not ancestors of 7, regardless of where their least common
ancestor is.

Merge preview not affected by common ancestor:

  $ hg up -q 7
  $ hg merge -q -P 6
  2:2d95304fed5d
  4:f25cbe84d8b3
  5:a431fabd6039
  6:e88e33f3bf62