tests/test-minirst.py

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

from mercurial import minirst
from mercurial.utils import stringutil


def debugformat(text, form, **kwargs):
    blocks, pruned = minirst.parse(text, **kwargs)
    if form == b'html':
        print("html format:")
        out = minirst.format(text, style=form, **kwargs)
    else:
        print("%d column format:" % form)
        out = minirst.format(text, width=form, **kwargs)

    print("-" * 70)
    print(out[:-1].decode('utf8'))
    if kwargs.get('keep'):
        print("-" * 70)
        print(stringutil.pprint(pruned).decode('utf8'))
    print("-" * 70)
    print()


def debugformats(title, text, **kwargs):
    print("== %s ==" % title)
    debugformat(text, 60, **kwargs)
    debugformat(text, 30, **kwargs)
    debugformat(text, b'html', **kwargs)


paragraphs = b"""
This is some text in the first paragraph.

  A small indented paragraph.
  It is followed by some lines
  containing random whitespace.
 \n  \n   \nThe third and final paragraph.
"""

debugformats('paragraphs', paragraphs)

definitions = b"""
A Term
  Definition. The indented
  lines make up the definition.
Another Term
  Another definition. The final line in the
   definition determines the indentation, so
    this will be indented with four spaces.

  A Nested/Indented Term
    Definition.
"""

debugformats('definitions', definitions)

literals = br"""
The fully minimized form is the most
convenient form::

  Hello
    literal
      world

In the partially minimized form a paragraph
simply ends with space-double-colon. ::

  ////////////////////////////////////////
  long un-wrapped line in a literal block
  \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\

::

  This literal block is started with '::',
    the so-called expanded form. The paragraph
      with '::' disappears in the final output.
"""

debugformats('literals', literals)

lists = b"""
- This is the first list item.

  Second paragraph in the first list item.

- List items need not be separated
  by a blank line.
- And will be rendered without
  one in any case.

We can have indented lists:

  - This is an indented list item

  - Another indented list item::

      - A literal block in the middle
            of an indented list.

      (The above is not a list item since we are in the literal block.)

::

  Literal block with no indentation (apart from
  the two spaces added to all literal blocks).

1. This is an enumerated list (first item).
2. Continuing with the second item.

(1) foo
(2) bar

1) Another
2) List

Line blocks are also a form of list:

| This is the first line.
  The line continues here.
| This is the second line.

Bullet lists are also detected:

* This is the first bullet
* This is the second bullet
  It has 2 lines
* This is the third bullet
"""

debugformats('lists', lists)

options = b"""
There is support for simple option lists,
but only with long options:

-X, --exclude  filter  an option with a short and long option with an argument
-I, --include          an option with both a short option and a long option
--all                  Output all.
--both                 Output both (this description is
                       quite long).
--long                 Output all day long.

--par                 This option has two paragraphs in its description.
                      This is the first.

                      This is the second.  Blank lines may be omitted between
                      options (as above) or left in (as here).


The next paragraph looks like an option list, but lacks the two-space
marker after the option. It is treated as a normal paragraph:

--foo bar baz
"""

debugformats('options', options)

fields = b"""
:a: First item.
:ab: Second item. Indentation and wrapping
     is handled automatically.
:c\:d: a key with colon
:efg\:\:hh: a key with many colon

Next list:

:small: The larger key below triggers full indentation here.
:much too large: This key is big enough to get its own line.
"""

debugformats('fields', fields)

containers = b"""
Normal output.

.. container:: debug

   Initial debug output.

.. container:: verbose

   Verbose output.

   .. container:: debug

      Debug output.
"""

debugformats('containers (normal)', containers)
debugformats('containers (verbose)', containers, keep=[b'verbose'])
debugformats('containers (debug)', containers, keep=[b'debug'])
debugformats(
    'containers (verbose debug)', containers, keep=[b'verbose', b'debug']
)

roles = b"""Please see :hg:`add`."""
debugformats('roles', roles)


sections = b"""
Title
=====

Section
-------

Subsection
''''''''''

Markup: ``foo`` and :hg:`help`
------------------------------
"""
debugformats('sections', sections)


admonitions = b"""
.. note::

   This is a note

   - Bullet 1
   - Bullet 2

   .. warning:: This is a warning Second
      input line of warning

.. danger::
   This is danger
"""

debugformats('admonitions', admonitions)

comments = b"""
Some text.

.. A comment

   .. An indented comment

   Some indented text.

..

Empty comment above
"""

debugformats('comments', comments)


data = [
    [b'a', b'b', b'c'],
    [b'1', b'2', b'3'],
    [b'foo', b'bar', b'baz this list is very very very long man'],
]

rst = minirst.maketable(data, 2, True)
table = b''.join(rst)

print(table.decode('utf8'))

debugformats('table', table)

data = [
    [b's', b'long', b'line\ngoes on here'],
    [b'', b'xy', b'tried to fix here\n        by indenting'],
]

rst = minirst.maketable(data, 1, False)
table = b''.join(rst)

print(table.decode('utf8'))

debugformats('table+nl', table)