tests/test-install.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

hg debuginstall
  $ hg debuginstall
  checking encoding (ascii)...
  checking Python executable (*) (glob)
  checking Python implementation (*) (glob)
  checking Python version (3.*) (glob) (py3 !)
  checking Python lib (.*[Ll]ib.*)... (re) (no-pyoxidizer !)
  checking Python lib (.*pyoxidizer.*)... (re) (pyoxidizer !)
  checking Python security support (*) (glob)
    TLS 1.2 not supported by Python install; network connections lack modern security (?)
    SNI not supported by Python install; may have connectivity issues with some servers (?)
  checking Rust extensions \((installed|missing)\) (re)
  checking Mercurial version (*) (glob)
  checking Mercurial custom build (*) (glob)
  checking module policy (*) (glob)
  checking installed modules (*mercurial)... (glob)
  checking registered compression engines (*zlib*) (glob)
  checking available compression engines (*zlib*) (glob)
  checking available compression engines for wire protocol (*zlib*) (glob)
  checking "re2" regexp engine \((available|missing)\) (re)
  checking templates (*mercurial?templates)... (glob) (no-pyoxidizer !)
  checking templates (*app?templates)... (glob) (pyoxidizer !)
  checking default template (*mercurial?templates?map-cmdline.default) (glob) (no-pyoxidizer !)
  checking default template (*app?templates?map-cmdline.default) (glob) (pyoxidizer !)
  checking commit editor... (*) (glob)
  checking username (test)
  no problems detected

hg debuginstall JSON
  $ hg debuginstall -Tjson | sed 's|\\\\|\\|g'
  [
   {
    "compengines": ["bz2", "bz2truncated", "none", "zlib"*], (glob)
    "compenginesavail": ["bz2", "bz2truncated", "none", "zlib"*], (glob)
    "compenginesserver": [*"zlib"*], (glob)
    "defaulttemplate": "*mercurial?templates?map-cmdline.default", (glob) (no-pyoxidizer !)
    "defaulttemplate": "*app?templates?map-cmdline.default", (glob) (pyoxidizer !)
    "defaulttemplateerror": null,
    "defaulttemplatenotfound": "default",
    "editor": "*", (glob)
    "editornotfound": false,
    "encoding": "ascii",
    "encodingerror": null,
    "extensionserror": null, (no-pure !)
    "hgmodulepolicy": "*", (glob)
    "hgmodules": "*mercurial", (glob)
    "hgver": "*", (glob)
    "hgverextra": "*", (glob)
    "problems": 0,
    "pythonexe": "*", (glob)
    "pythonimplementation": "*", (glob)
    "pythonlib": "*", (glob)
    "pythonsecurity": [*], (glob)
    "pythonver": "*.*.*", (glob)
    "re2": (true|false), (re)
    "templatedirs": "*mercurial?templates", (glob) (no-pyoxidizer !)
    "templatedirs": "*app?templates", (glob) (pyoxidizer !)
    "username": "test",
    "usernameerror": null,
    "vinotfound": false
   }
  ]

hg debuginstall with no username
  $ HGUSER= hg debuginstall
  checking encoding (ascii)...
  checking Python executable (*) (glob)
  checking Python implementation (*) (glob)
  checking Python version (3.*) (glob) (py3 !)
  checking Python lib (.*[Ll]ib.*)... (re) (no-pyoxidizer !)
  checking Python lib (.*pyoxidizer.*)... (re) (pyoxidizer !)
  checking Python security support (*) (glob)
    TLS 1.2 not supported by Python install; network connections lack modern security (?)
    SNI not supported by Python install; may have connectivity issues with some servers (?)
  checking Rust extensions \((installed|missing)\) (re)
  checking Mercurial version (*) (glob)
  checking Mercurial custom build (*) (glob)
  checking module policy (*) (glob)
  checking installed modules (*mercurial)... (glob)
  checking registered compression engines (*zlib*) (glob)
  checking available compression engines (*zlib*) (glob)
  checking available compression engines for wire protocol (*zlib*) (glob)
  checking "re2" regexp engine \((available|missing)\) (re)
  checking templates (*mercurial?templates)... (glob) (no-pyoxidizer !)
  checking templates (*app?templates)... (glob) (pyoxidizer !)
  checking default template (*mercurial?templates?map-cmdline.default) (glob) (no-pyoxidizer !)
  checking default template (*app?templates?map-cmdline.default) (glob) (pyoxidizer !)
  checking commit editor... (*) (glob)
  checking username...
   no username supplied
   (specify a username in your configuration file)
  1 problems detected, please check your install!
  [1]

hg debuginstall with invalid encoding
  $ HGENCODING=invalidenc hg debuginstall | grep encoding
  checking encoding (invalidenc)...
   unknown encoding: invalidenc

exception message in JSON

  $ HGENCODING=invalidenc HGUSER= hg debuginstall -Tjson | grep error
    "defaulttemplateerror": null,
    "encodingerror": "unknown encoding: invalidenc",
    "extensionserror": null, (no-pure !)
    "usernameerror": "no username supplied",

path variables are expanded (~ is the same as $TESTTMP)
  $ mkdir tools
  $ touch tools/testeditor.exe
#if execbit
  $ chmod 755 tools/testeditor.exe
#endif
  $ HGEDITOR="~/tools/testeditor.exe" hg debuginstall
  checking encoding (ascii)...
  checking Python executable (*) (glob)
  checking Python implementation (*) (glob)
  checking Python version (3.*) (glob) (py3 !)
  checking Python lib (.*[Ll]ib.*)... (re) (no-pyoxidizer !)
  checking Python lib (.*pyoxidizer.*)... (re) (pyoxidizer !)
  checking Python security support (*) (glob)
    TLS 1.2 not supported by Python install; network connections lack modern security (?)
    SNI not supported by Python install; may have connectivity issues with some servers (?)
  checking Rust extensions \((installed|missing)\) (re)
  checking Mercurial version (*) (glob)
  checking Mercurial custom build (*) (glob)
  checking module policy (*) (glob)
  checking installed modules (*mercurial)... (glob)
  checking registered compression engines (*zlib*) (glob)
  checking available compression engines (*zlib*) (glob)
  checking available compression engines for wire protocol (*zlib*) (glob)
  checking "re2" regexp engine \((available|missing)\) (re)
  checking templates (*mercurial?templates)... (glob) (no-pyoxidizer !)
  checking templates (*app?templates)... (glob) (pyoxidizer !)
  checking default template (*mercurial?templates?map-cmdline.default) (glob) (no-pyoxidizer !)
  checking default template (*app?templates?map-cmdline.default) (glob) (pyoxidizer !)
  checking commit editor... ($TESTTMP/tools/testeditor.exe)
  checking username (test)
  no problems detected

print out the binary post-shlexsplit in the error message when commit editor is
not found (this is intentionally using backslashes to mimic a windows usecase).
  $ HGEDITOR="c:\foo\bar\baz.exe -y -z" hg debuginstall
  checking encoding (ascii)...
  checking Python executable (*) (glob)
  checking Python implementation (*) (glob)
  checking Python version (3.*) (glob) (py3 !)
  checking Python lib (.*[Ll]ib.*)... (re) (no-pyoxidizer !)
  checking Python lib (.*pyoxidizer.*)... (re) (pyoxidizer !)
  checking Python security support (*) (glob)
    TLS 1.2 not supported by Python install; network connections lack modern security (?)
    SNI not supported by Python install; may have connectivity issues with some servers (?)
  checking Rust extensions \((installed|missing)\) (re)
  checking Mercurial version (*) (glob)
  checking Mercurial custom build (*) (glob)
  checking module policy (*) (glob)
  checking installed modules (*mercurial)... (glob)
  checking registered compression engines (*zlib*) (glob)
  checking available compression engines (*zlib*) (glob)
  checking available compression engines for wire protocol (*zlib*) (glob)
  checking "re2" regexp engine \((available|missing)\) (re)
  checking templates (*mercurial?templates)... (glob) (no-pyoxidizer !)
  checking templates (*app?templates)... (glob) (pyoxidizer !)
  checking default template (*mercurial?templates?map-cmdline.default) (glob) (no-pyoxidizer !)
  checking default template (*app?templates?map-cmdline.default) (glob) (pyoxidizer !)
  checking commit editor... (c:\foo\bar\baz.exe) (windows !)
   Can't find editor 'c:\foo\bar\baz.exe' in PATH (windows !)
  checking commit editor... (c:foobarbaz.exe) (no-windows !)
   Can't find editor 'c:foobarbaz.exe' in PATH (no-windows !)
   (specify a commit editor in your configuration file)
  checking username (test)
  1 problems detected, please check your install!
  [1]

debuginstall extension support
  $ hg debuginstall --config extensions.fsmonitor= --config fsmonitor.watchman_exe=false | grep atchman
  fsmonitor checking for watchman binary... (false)
   watchman binary missing or broken: warning: Watchman unavailable: watchman exited with code 1
Verify the json works too:
  $ hg debuginstall --config extensions.fsmonitor= --config fsmonitor.watchman_exe=false -Tjson | grep atchman
    "fsmonitor-watchman": "false",
    "fsmonitor-watchman-error": "warning: Watchman unavailable: watchman exited with code 1",

Verify that Mercurial is installable with pip. Note that this MUST be
the last test in this file, because we do some nasty things to the
shell environment in order to make the virtualenv work reliably.

On Python 3, we use the venv module, which is part of the standard library.
But some Linux distros strip out this module's functionality involving pip,
so we have to look for the ensurepip module, which these distros strip out
completely.
On Python 2, we use the 3rd party virtualenv module, if available.

  $ cd $TESTTMP
  $ unset PYTHONPATH

#if py3 ensurepip network-io no-pyoxidizer
  $ "$PYTHON" -m venv installenv >> pip.log

Hack: Debian does something a bit different in ensurepip.bootstrap. This makes
it so that pip thinks the 'wheel' wheel is installed so it can build wheels;
when it goes to try, however, it shells out to run `python3 -u <setup.py>`,
that *doesn't* get the 'wheel' wheel, and it fails with an invalid command
'bdist_wheel'. To fix this, we just delete the wheel from where Debian put it in
our virtual env. Then pip doesn't think it's installed and doesn't try to build.
  $ rm installenv/share/python-wheels/wheel-*.whl >/dev/null 2>&1 || true

Note: we use this weird path to run pip and hg to avoid platform differences,
since it's bin on most platforms but Scripts on Windows.
  $ ./installenv/*/pip install $TESTDIR/.. >> pip.log
    Failed building wheel for mercurial (?)
  WARNING: You are using pip version *; however, version * is available. (glob) (?)
  You should consider upgrading via the '$TESTTMP/installenv/bin/python* -m pip install --upgrade pip' command. (glob) (?)
  $ ./installenv/*/hg debuginstall || cat pip.log
  checking encoding (ascii)...
  checking Python executable (*) (glob)
  checking Python implementation (*) (glob)
  checking Python version (3.*) (glob)
  checking Python lib (*)... (glob)
  checking Python security support (*) (glob)
  checking Rust extensions \((installed|missing)\) (re)
  checking Mercurial version (*) (glob)
  checking Mercurial custom build (*) (glob)
  checking module policy (*) (glob)
  checking installed modules (*/mercurial)... (glob)
  checking registered compression engines (*) (glob)
  checking available compression engines (*) (glob)
  checking available compression engines for wire protocol (*) (glob)
  checking "re2" regexp engine \((available|missing)\) (re)
  checking templates ($TESTTMP/installenv/*/site-packages/mercurial/templates)... (glob)
  checking default template ($TESTTMP/installenv/*/site-packages/mercurial/templates/map-cmdline.default) (glob)
  checking commit editor... (*) (glob)
  checking username (test)
  no problems detected
#endif

#if virtualenv no-py3 network-io no-pyoxidizer

Note: --no-site-packages is the default for all versions enabled by hghave

  $ "$PYTHON" -m virtualenv installenv >> pip.log
  DEPRECATION: Python 2.7 will reach the end of its life on January 1st, 2020. Please upgrade your Python as Python 2.7 won't be maintained after that date. A future version of pip will drop support for Python 2.7. (?)
  DEPRECATION: Python 2.7 will reach the end of its life on January 1st, 2020. Please upgrade your Python as Python 2.7 won't be maintained after that date. A future version of pip will drop support for Python 2.7. More details about Python 2 support in pip, can be found at https://pip.pypa.io/en/latest/development/release-process/#python-2-support (?)

Note: we use this weird path to run pip and hg to avoid platform differences,
since it's bin on most platforms but Scripts on Windows.
  $ ./installenv/*/pip install $TESTDIR/.. >> pip.log
  DEPRECATION: Python 2.7 will reach the end of its life on January 1st, 2020. Please upgrade your Python as Python 2.7 won't be maintained after that date. A future version of pip will drop support for Python 2.7. (?)
  DEPRECATION: Python 2.7 will reach the end of its life on January 1st, 2020. Please upgrade your Python as Python 2.7 won't be maintained after that date. A future version of pip will drop support for Python 2.7. More details about Python 2 support in pip, can be found at https://pip.pypa.io/en/latest/development/release-process/#python-2-support (?)
  DEPRECATION: Python 2.7 reached the end of its life on January 1st, 2020. Please upgrade your Python as Python 2.7 is no longer maintained. pip 21.0 will drop support for Python 2.7 in January 2021. More details about Python 2 support in pip can be found at https://pip.pypa.io/en/latest/development/release-process/#python-2-support pip 21.0 will remove support for this functionality. (?)
  $ ./installenv/*/hg debuginstall || cat pip.log
  checking encoding (ascii)...
  checking Python executable (*) (glob)
  checking Python implementation (*) (glob)
  checking Python version (2.*) (glob)
  checking Python lib (*)... (glob)
  checking Python security support (*) (glob)
    TLS 1.2 not supported by Python install; network connections lack modern security (?)
    SNI not supported by Python install; may have connectivity issues with some servers (?)
  checking Rust extensions \((installed|missing)\) (re)
  checking Mercurial version (*) (glob)
  checking Mercurial custom build (*) (glob)
  checking module policy (*) (glob)
  checking installed modules (*/mercurial)... (glob)
  checking registered compression engines (*) (glob)
  checking available compression engines (*) (glob)
  checking available compression engines for wire protocol (*) (glob)
  checking "re2" regexp engine \((available|missing)\) (re)
  checking templates ($TESTTMP/installenv/*/site-packages/mercurial/templates)... (glob)
  checking default template ($TESTTMP/installenv/*/site-packages/mercurial/templates/map-cmdline.default) (glob)
  checking commit editor... (*) (glob)
  checking username (test)
  no problems detected
#endif