tests/test-convert-bzr-merges.t

merge: minimize conflicts when common base is not shown (issue4447)

Previously, two changes that were nearly, but not quite, identical would result
in large merge conflict regions that looked very similar, and were thus very
confusing to users, and lead people used to other source control systems to
claim that "mercurial's merge algorithms suck". In the relatively common case
of a new file being introduced in two branches with very slight modifications,
the old behavior would show the entire file as a conflict, and it would be very
difficult for a user to determine what was going on.

In the past, mercurial attempted to solve this with a "very smart" algorithm
that would find all common lines, but this has significant problems as
described in 2ea6d906cf9b.

Instead, we use a "very dumb" algorithm introduced in the previous patch that
simply matches lines at the periphery of conflict regions. This minimizes most
conflict regions well, though there may still be some degenerate edge cases,
like small modification to the beginning and end of a large file.

#require bzr

N.B. bzr 1.13 has a bug that breaks this test.  If you see this
test fail, check your bzr version.  Upgrading to bzr 1.13.1
should fix it.

  $ . "$TESTDIR/bzr-definitions"

test multiple merges at once

  $ mkdir test-multimerge
  $ cd test-multimerge
  $ bzr init -q source
  $ cd source
  $ echo content > file
  $ bzr add -q file
  $ bzr commit -q -m 'Initial add'
  $ cd ..
  $ bzr branch -q source source-branch1
  $ cd source-branch1
  $ echo morecontent >> file
  $ echo evenmorecontent > file-branch1
  $ bzr add -q file-branch1
  $ bzr commit -q -m 'Added branch1 file'
  $ cd ../source
  $ sleep 1
  $ echo content > file-parent
  $ bzr add -q file-parent
  $ bzr commit -q -m 'Added parent file'
  $ cd ..
  $ bzr branch -q source source-branch2
  $ cd source-branch2
  $ echo somecontent > file-branch2
  $ bzr add -q file-branch2
  $ bzr commit -q -m 'Added brach2 file'
  $ sleep 1
  $ cd ../source
  $ bzr merge -q ../source-branch1
  $ bzr merge -q --force ../source-branch2
  $ bzr commit -q -m 'Merged branches'
  $ cd ..
  $ hg convert --datesort source source-hg
  initializing destination source-hg repository
  scanning source...
  sorting...
  converting...
  4 Initial add
  3 Added branch1 file
  2 Added parent file
  1 Added brach2 file
  0 Merged branches
  $ glog -R source-hg
  o    5@source "(octopus merge fixup)" files:
  |\
  | o    4@source "Merged branches" files: file-branch2
  | |\
  o---+  3@source-branch2 "Added brach2 file" files: file-branch2
   / /
  | o  2@source "Added parent file" files: file-parent
  | |
  o |  1@source-branch1 "Added branch1 file" files: file file-branch1
  |/
  o  0@source "Initial add" files: file
  
  $ manifest source-hg tip
  % manifest of tip
  644   file
  644   file-branch1
  644   file-branch2
  644   file-parent

  $ cd ..