tests/test-bookflow.t

filemerge: add support for partial conflict resolution by external tool

A common class of merge conflicts is in imports/#includes/etc. It's
relatively easy to write a tool that can resolve these conflicts,
perhaps by naively just unioning the statements and leaving any
cleanup to other tools to do later [1]. Such specialized tools cannot
generally resolve all conflicts in a file, of course. Let's therefore
call them "partial merge tools". Note that the internal simplemerge
algorithm is such a partial merge tool - one that only resolves
trivial "conflicts" where one side is unchanged or both sides change
in the same way.

One can also imagine having smarter language-aware partial tools that
merge the AST. It may be useful for such tools to interactively let
the user resolve any conflicts it can't resolve itself. However,
having the option of implementing it as a partial merge tool means
that the developer doesn't *need* to create a UI for it. Instead, the
user can resolve any remaining conflicts with their regular merge tool
(e.g. `:merge3` or `meld).

We don't currently have a way to let the user define such partial
merge tools. That's what this patch addresses. It lets the user
configure partial merge tools to run. Each tool can be configured to
run only on files matching certain patterns (e.g. "*.py"). The tool
takes three inputs (local, base, other) and resolves conflicts by
updating these in place. For example, let's say the inputs are these:


base:
```
import sys

def main():
  print('Hello')
```

local:
```
import os
import sys

def main():
  print('Hi')
```

other:
```
import re
import sys

def main():
  print('Howdy')
```

A partial merge tool could now resolve the conflicting imports by
replacing the import statements in *all* files by the following
snippet, while leaving the remainder of the files unchanged.

```
import os
import re
import sys
```

As a result, simplemerge and any regular merge tool that runs after
the partial merge tool(s) will consider the imports to be
non-conflicting and will only present the conflict in `main()` to the
user.

Differential Revision: https://phab.mercurial-scm.org/D12356

initialize
  $ make_changes() {
  >     d=`pwd`
  >     [ ! -z $1 ] && cd $1
  >     echo "test `basename \`pwd\``" >> test
  >     hg commit -Am"${2:-test}"
  >     r=$?
  >     cd $d
  >     return $r
  > }
  $ ls -1a
  .
  ..
  $ hg init a
  $ cd a
  $ echo 'test' > test; hg commit -Am'test'
  adding test

clone to b

  $ mkdir ../b
  $ cd ../b
  $ hg clone ../a .
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ echo "[extensions]" >> .hg/hgrc
  $ echo "bookflow=" >> .hg/hgrc
  $ hg branch X
  abort: creating named branches is disabled and you should use bookmarks
  (see 'hg help bookflow')
  [255]
  $ hg bookmark X
  $ hg bookmarks
  * X                         0:* (glob)
  $ hg bookmark X
  abort: bookmark X already exists, to move use the --rev option
  [255]
  $ make_changes
  $ hg push ../a -q

  $ hg bookmarks
   \* X                         1:* (glob)

change a
  $ cd ../a
  $ hg up
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ echo 'test' >> test; hg commit -Am'test'


pull in b
  $ cd ../b
  $ hg pull -u
  pulling from $TESTTMP/a
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files
  new changesets * (glob)
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (leaving bookmark X)
  $ hg status
  $ hg bookmarks
     X                         1:* (glob)

check protection of @ bookmark
  $ hg bookmark @
  $ hg bookmarks
   \* @                         2:* (glob)
     X                         1:* (glob)
  $ make_changes
  abort: cannot commit, bookmark @ is protected
  [255]

  $ hg status
  M test
  $ hg bookmarks
   \* @                         2:* (glob)
     X                         1:* (glob)

  $ hg --config bookflow.protect= commit  -Am"Updated test"

  $ hg bookmarks
   \* @                         3:* (glob)
     X                         1:* (glob)

check requirement for an active bookmark
  $ hg bookmark -i
  $ hg bookmarks
     @                         3:* (glob)
     X                         1:* (glob)
  $ make_changes
  abort: cannot commit without an active bookmark
  [255]
  $ hg revert test
  $ rm test.orig
  $ hg status


make the bookmark move by updating it on a, and then pulling
# add a commit to a
  $ cd ../a
  $ hg bookmark X
  $ hg bookmarks
   \* X                         2:* (glob)
  $ make_changes
  $ hg bookmarks
   * X                         3:81af7977fdb9

# go back to b, and check out X
  $ cd ../b
  $ hg up X
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (activating bookmark X)
  $ hg bookmarks
     @                         3:* (glob)
   \* X                         1:* (glob)

# pull, this should move the bookmark forward, because it was changed remotely
  $ hg pull -u | grep "updating to active bookmark X"
  updating to active bookmark X

  $ hg bookmarks
     @                         3:* (glob)
   * X                         4:81af7977fdb9

the bookmark should not move if it diverged from remote
  $ hg -R ../a status
  $ hg -R ../b status
  $ make_changes ../a
  $ make_changes ../b
  $ hg -R ../a status
  $ hg -R ../b status
  $ hg -R ../a bookmarks
   * X                         4:238292f60a57
  $ hg -R ../b bookmarks
     @                         3:* (glob)
   * X                         5:096f7e86892d
  $ cd ../b
  $ # make sure we cannot push after bookmarks diverged
  $ hg push -B X | grep abort
  abort: push creates new remote head * with bookmark 'X' (glob)
  (pull and merge or see 'hg help push' for details about pushing new heads)
  [1]
  $ hg pull -u | grep divergent
  divergent bookmark X stored as X@default
  1 other divergent bookmarks for "X"
  $ hg bookmarks
     @                         3:* (glob)
   * X                         5:096f7e86892d
     X@default                 6:238292f60a57
  $ hg id -in
  096f7e86892d 5
  $ make_changes
  $ hg status
  $ hg bookmarks
     @                         3:* (glob)
   * X                         7:227f941aeb07
     X@default                 6:238292f60a57

now merge with the remote bookmark
  $ hg merge X@default --tool :local -q
  $ hg status
  M test
  $ hg commit -m"Merged with X@default"
  $ hg bookmarks
     @                         3:* (glob)
   * X                         8:26fed9bb3219
  $ hg push -B X | grep bookmark
  pushing to $TESTTMP/a (?)
  updating bookmark X
  $ cd ../a
  $ hg up -q
  $ hg bookmarks
   * X                         7:26fed9bb3219

test hg pull when there is more than one descendant
  $ cd ../a
  $ hg bookmark Z
  $ hg bookmark Y
  $ make_changes . YY
  $ hg up Z -q
  $ make_changes . ZZ
  created new head
  $ hg bookmarks
     X                         7:26fed9bb3219
     Y                         8:131e663dbd2a
   * Z                         9:b74a4149df25
  $ hg log -r 'p1(Y)' -r 'p1(Z)' -T '{rev}\n' # prove that Y and Z share the same parent
  7
  $ hg log -r 'Y%Z' -T '{rev}\n'  # revs in Y but not in Z
  8
  $ hg log -r 'Z%Y' -T '{rev}\n'  # revs in Z but not in Y
  9
  $ cd ../b
  $ hg pull -uq
  $ hg id
  b74a4149df25 tip Z
  $ hg bookmarks | grep \*  # no active bookmark
  [1]


test shelving
  $ cd ../a
  $ echo anotherfile > anotherfile # this change should not conflict
  $ hg add anotherfile
  $ hg commit -m"Change in a"
  $ cd ../b
  $ hg up Z | grep Z
  (activating bookmark Z)
  $ hg book | grep \* # make sure active bookmark
   \* Z                         10:* (glob)
  $ echo "test b" >> test
  $ hg diff --stat
   test |  1 +
   1 files changed, 1 insertions(+), 0 deletions(-)
  $ hg shelve
  shelved as Z
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg pull -uq
  $ hg unshelve
  unshelving change 'Z'
  rebasing shelved changes
  $ hg diff --stat
   test |  1 +
   1 files changed, 1 insertions(+), 0 deletions(-)


make the bookmark move by updating it on a, and then pulling with a local change
# add a commit to a
  $ cd ../a
  $ hg up -C X |fgrep  "activating bookmark X"
  (activating bookmark X)
# go back to b, and check out X
  $ cd ../b
  $ hg up -C X |fgrep  "activating bookmark X"
  (activating bookmark X)
# update and push from a
  $ make_changes ../a
  created new head
  $ echo "more" >> test
  $ hg pull -u 2>&1 | fgrep -v TESTTMP| fgrep -v "searching for changes" | fgrep -v adding
  pulling from $TESTTMP/a
  updating bookmark X
  added 1 changesets with 0 changes to 0 files (+1 heads)
  new changesets * (glob)
  updating to active bookmark X
  merging test
  warning: conflicts while merging test! (edit, then use 'hg resolve --mark')
  0 files updated, 0 files merged, 0 files removed, 1 files unresolved
  use 'hg resolve' to retry unresolved file merges
  $ hg update -Cq
  $ rm test.orig

make sure that commits aren't possible if working directory is not pointing to active bookmark
  $ hg -R ../a status
  $ hg -R ../b status
  $ hg -R ../a id -i
  36a6e592ec06
  $ hg -R ../a book | grep X
   \* X                         \d+:36a6e592ec06 (re)
  $ hg -R ../b id -i
  36a6e592ec06
  $ hg -R ../b book | grep X
   \* X                         \d+:36a6e592ec06 (re)
  $ make_changes ../a
  $ hg -R ../a book | grep X
   \* X                         \d+:f73a71c992b8 (re)
  $ cd ../b
  $ hg pull  2>&1 | grep -v add | grep -v pulling | grep -v searching | grep -v changeset
  updating bookmark X
  (run 'hg update' to get a working copy)
  working directory out of sync with active bookmark, run 'hg up X'
  $ hg id -i # we're still on the old commit
  36a6e592ec06
  $ hg book | grep X # while the bookmark moved
   \* X                         \d+:f73a71c992b8 (re)
  $ make_changes
  abort: cannot commit, working directory out of sync with active bookmark
  (run 'hg up X')
  [255]
  $ hg up -Cq -r .  # cleanup local changes
  $ hg status
  $ hg id -i # we're still on the old commit
  36a6e592ec06
  $ hg up X -q
  $ hg id -i # now we're on X
  f73a71c992b8
  $ hg book | grep X
   \* X                         \d+:f73a71c992b8 (re)