tests/test-convert-datesort.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

  $ cat >> $HGRCPATH <<EOF
  > [extensions]
  > convert=
  > EOF
  $ hg init t
  $ cd t
  $ echo a >> a
  $ hg ci -Am a0 -d '1 0'
  adding a
  $ hg branch brancha
  marked working directory as branch brancha
  (branches are permanent and global, did you want a bookmark?)
  $ echo a >> a
  $ hg ci -m a1 -d '2 0'
  $ echo a >> a
  $ hg ci -m a2 -d '3 0'
  $ echo a >> a
  $ hg ci -m a3 -d '4 0'
  $ hg up -C 0
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg branch branchb
  marked working directory as branch branchb
  $ echo b >> b
  $ hg ci -Am b0 -d '6 0'
  adding b
  $ hg up -C brancha
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ echo a >> a
  $ hg ci -m a4 -d '5 0'
  $ echo a >> a
  $ hg ci -m a5 -d '7 0'
  $ echo a >> a
  $ hg ci -m a6 -d '8 0'
  $ hg up -C branchb
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ echo b >> b
  $ hg ci -m b1 -d '9 0'
  $ hg up -C 0
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ echo c >> c
  $ hg branch branchc
  marked working directory as branch branchc
  $ hg ci -Am c0 -d '10 0'
  adding c
  $ hg up -C brancha
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ hg ci --close-branch -m a7x -d '11 0'
  $ hg up -C branchb
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg ci --close-branch -m b2x -d '12 0'
  $ hg up -C branchc
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ hg merge branchb
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ hg ci -m c1 -d '13 0'
  $ cd ..

convert with datesort

  $ hg convert --datesort t t-datesort
  initializing destination t-datesort repository
  scanning source...
  sorting...
  converting...
  12 a0
  11 a1
  10 a2
  9 a3
  8 a4
  7 b0
  6 a5
  5 a6
  4 b1
  3 c0
  2 a7x
  1 b2x
  0 c1

graph converted repo

  $ hg -R t-datesort log -G --template '{rev} "{desc}"\n'
  o    12 "c1"
  |\
  | _  11 "b2x"
  | |
  | | _  10 "a7x"
  | | |
  o | |  9 "c0"
  | | |
  | o |  8 "b1"
  | | |
  | | o  7 "a6"
  | | |
  | | o  6 "a5"
  | | |
  | o |  5 "b0"
  |/ /
  | o  4 "a4"
  | |
  | o  3 "a3"
  | |
  | o  2 "a2"
  | |
  | o  1 "a1"
  |/
  o  0 "a0"
  

convert with datesort (default mode)

  $ hg convert t t-sourcesort
  initializing destination t-sourcesort repository
  scanning source...
  sorting...
  converting...
  12 a0
  11 a1
  10 a2
  9 a3
  8 b0
  7 a4
  6 a5
  5 a6
  4 b1
  3 c0
  2 a7x
  1 b2x
  0 c1

graph converted repo

  $ hg -R t-sourcesort log -G --template '{rev} "{desc}"\n'
  o    12 "c1"
  |\
  | _  11 "b2x"
  | |
  | | _  10 "a7x"
  | | |
  o | |  9 "c0"
  | | |
  | o |  8 "b1"
  | | |
  | | o  7 "a6"
  | | |
  | | o  6 "a5"
  | | |
  | | o  5 "a4"
  | | |
  | o |  4 "b0"
  |/ /
  | o  3 "a3"
  | |
  | o  2 "a2"
  | |
  | o  1 "a1"
  |/
  o  0 "a0"
  

convert with closesort

  $ hg convert --closesort t t-closesort
  initializing destination t-closesort repository
  scanning source...
  sorting...
  converting...
  12 a0
  11 a1
  10 a2
  9 a3
  8 b0
  7 a4
  6 a5
  5 a6
  4 a7x
  3 b1
  2 b2x
  1 c0
  0 c1

graph converted repo

  $ hg -R t-closesort log -G --template '{rev} "{desc}"\n'
  o    12 "c1"
  |\
  | o  11 "c0"
  | |
  _ |  10 "b2x"
  | |
  o |  9 "b1"
  | |
  | | _  8 "a7x"
  | | |
  | | o  7 "a6"
  | | |
  | | o  6 "a5"
  | | |
  | | o  5 "a4"
  | | |
  o | |  4 "b0"
  |/ /
  | o  3 "a3"
  | |
  | o  2 "a2"
  | |
  | o  1 "a1"
  |/
  o  0 "a0"