tests/test-doctest.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

# this is hack to make sure no escape characters are inserted into the output


import doctest
import os
import re
import subprocess
import sys

ispy3 = sys.version_info[0] >= 3

if 'TERM' in os.environ:
    del os.environ['TERM']


class py3docchecker(doctest.OutputChecker):
    def check_output(self, want, got, optionflags):
        want2 = re.sub(r'''\bu(['"])(.*?)\1''', r'\1\2\1', want)  # py2: u''
        got2 = re.sub(r'''\bb(['"])(.*?)\1''', r'\1\2\1', got)  # py3: b''
        # py3: <exc.name>: b'<msg>' -> <name>: <msg>
        #      <exc.name>: <others> -> <name>: <others>
        got2 = re.sub(
            r'''^mercurial\.\w+\.(\w+): (['"])(.*?)\2''',
            r'\1: \3',
            got2,
            re.MULTILINE,
        )
        got2 = re.sub(r'^mercurial\.\w+\.(\w+): ', r'\1: ', got2, re.MULTILINE)
        return any(
            doctest.OutputChecker.check_output(self, w, g, optionflags)
            for w, g in [(want, got), (want2, got2)]
        )


def testmod(name, optionflags=0, testtarget=None):
    __import__(name)
    mod = sys.modules[name]
    if testtarget is not None:
        mod = getattr(mod, testtarget)

    # minimal copy of doctest.testmod()
    finder = doctest.DocTestFinder()
    checker = None
    if ispy3:
        checker = py3docchecker()
    runner = doctest.DocTestRunner(checker=checker, optionflags=optionflags)
    for test in finder.find(mod, name):
        runner.run(test)
    runner.summarize()


DONT_RUN = []

# Exceptions to the defaults for a given detected module. The value for each
# module name is a list of dicts that specify the kwargs to pass to testmod.
# testmod is called once per item in the list, so an empty list will cause the
# module to not be tested.
testmod_arg_overrides = {
    'i18n.check-translation': DONT_RUN,  # may require extra installation
    'mercurial.dagparser': [{'optionflags': doctest.NORMALIZE_WHITESPACE}],
    'mercurial.keepalive': DONT_RUN,  # >>> is an example, not a doctest
    'mercurial.posix': DONT_RUN,  # run by mercurial.platform
    'mercurial.statprof': DONT_RUN,  # >>> is an example, not a doctest
    'mercurial.util': [{}, {'testtarget': 'platform'}],  # run twice!
    'mercurial.windows': DONT_RUN,  # run by mercurial.platform
    'tests.test-url': [{'optionflags': doctest.NORMALIZE_WHITESPACE}],
}

fileset = 'set:(**.py)'

cwd = os.path.dirname(os.environ["TESTDIR"])

if not os.path.isdir(os.path.join(cwd, ".hg")):
    sys.exit(0)

files = subprocess.check_output(
    "hg files --print0 \"%s\"" % fileset,
    shell=True,
    cwd=cwd,
).split(b'\0')

if sys.version_info[0] >= 3:
    cwd = os.fsencode(cwd)

mods_tested = set()
for f in files:
    if not f:
        continue

    with open(os.path.join(cwd, f), "rb") as fh:
        if not re.search(br'\n\s*>>>', fh.read()):
            continue

    if ispy3:
        f = f.decode()

    modname = f.replace('.py', '').replace('\\', '.').replace('/', '.')

    # Third-party modules aren't our responsibility to test, and the modules in
    # contrib generally do not have doctests in a good state, plus they're hard
    # to import if this test is running with py2, so we just skip both for now.
    if modname.startswith('mercurial.thirdparty.') or modname.startswith(
        'contrib.'
    ):
        continue

    for kwargs in testmod_arg_overrides.get(modname, [{}]):
        mods_tested.add((modname, '%r' % (kwargs,)))
        if modname.startswith('tests.'):
            # On py2, we can't import from tests.foo, but it works on both py2
            # and py3 with the way that PYTHONPATH is setup to import without
            # the 'tests.' prefix, so we do that.
            modname = modname[len('tests.') :]

        testmod(modname, **kwargs)

# Meta-test: let's make sure that we actually ran what we expected to, above.
# Each item in the set is a 2-tuple of module name and stringified kwargs passed
# to testmod.
expected_mods_tested = set(
    [
        ('hgext.convert.convcmd', '{}'),
        ('hgext.convert.cvsps', '{}'),
        ('hgext.convert.filemap', '{}'),
        ('hgext.convert.p4', '{}'),
        ('hgext.convert.subversion', '{}'),
        ('hgext.fix', '{}'),
        ('hgext.mq', '{}'),
        ('mercurial.changelog', '{}'),
        ('mercurial.cmdutil', '{}'),
        ('mercurial.color', '{}'),
        ('mercurial.dagparser', "{'optionflags': 4}"),
        ('mercurial.dirstateutils.v2', '{}'),
        ('mercurial.encoding', '{}'),
        ('mercurial.fancyopts', '{}'),
        ('mercurial.formatter', '{}'),
        ('mercurial.hg', '{}'),
        ('mercurial.hgweb.hgwebdir_mod', '{}'),
        ('mercurial.match', '{}'),
        ('mercurial.mdiff', '{}'),
        ('mercurial.minirst', '{}'),
        ('mercurial.parser', '{}'),
        ('mercurial.patch', '{}'),
        ('mercurial.pathutil', '{}'),
        ('mercurial.pycompat', '{}'),
        ('mercurial.revlogutils.deltas', '{}'),
        ('mercurial.revset', '{}'),
        ('mercurial.revsetlang', '{}'),
        ('mercurial.simplemerge', '{}'),
        ('mercurial.smartset', '{}'),
        ('mercurial.store', '{}'),
        ('mercurial.subrepo', '{}'),
        ('mercurial.templater', '{}'),
        ('mercurial.ui', '{}'),
        ('mercurial.util', "{'testtarget': 'platform'}"),
        ('mercurial.util', '{}'),
        ('mercurial.utils.dateutil', '{}'),
        ('mercurial.utils.stringutil', '{}'),
        ('mercurial.utils.urlutil', '{}'),
        ('tests.drawdag', '{}'),
        ('tests.test-run-tests', '{}'),
        ('tests.test-url', "{'optionflags': 4}"),
    ]
)

unexpectedly_run = mods_tested.difference(expected_mods_tested)
not_run = expected_mods_tested.difference(mods_tested)

if unexpectedly_run:
    print('Unexpectedly ran (probably need to add to list):')
    for r in sorted(unexpectedly_run):
        print('  %r' % (r,))
if not_run:
    print('Expected to run, but was not run (doctest removed?):')
    for r in sorted(not_run):
        print('  %r' % (r,))