tests/test-check-code.t

posix: always seek to EOF when opening a file in append mode

Python 3 already does this, so skip it there.

Consider the program:

   #include <stdio.h>

   int main() {
     FILE *f = fopen("narf", "w");
     fprintf(f, "narf\n");
     fclose(f);

     f = fopen("narf", "a");
     printf("%ld\n", ftell(f));
     fprintf(f, "troz\n");
     printf("%ld\n", ftell(f));

     return 0;
   }

on macOS, FreeBSD, and Linux with glibc, this program prints

   5
   10

but on musl libc (Alpine Linux and probably others) this prints

   0
   10

By my reading of
https://pubs.opengroup.org/onlinepubs/009695399/functions/fopen.html
this is technically correct, specifically:

> Opening a file with append mode (a as the first character in the
> mode argument) shall cause all subsequent writes to the file to be
> forced to the then current end-of-file, regardless of intervening
> calls to fseek().

in other words, the file position doesn't really matter in append-mode
files, and we can't depend on it being at all meaningful unless we
perform a seek() before tell() after open(..., 'a'). Experimentally
after a .write() we can do a .tell() and it'll always be reasonable,
but I'm unclear from reading the specification if that's a smart thing
to rely on. This matches what we do on Windows and what Python 3 does
for free, so let's just be consistent. Thanks to Yuya for the idea.

#require test-repo

  $ . "$TESTDIR/helpers-testrepo.sh"
  $ check_code="$TESTDIR"/../contrib/check-code.py
  $ cd "$TESTDIR"/..

New errors are not allowed. Warnings are strongly discouraged.
(The writing "no-che?k-code" is for not skipping this file when checking.)

  $ testrepohg locate \
  > -X contrib/python-zstandard \
  > -X hgext/fsmonitor/pywatchman \
  > -X mercurial/thirdparty \
  > | sed 's-\\-/-g' | "$check_code" --warnings --per-file=0 - || false
  Skipping contrib/automation/hgautomation/__init__.py it has no-che?k-code (glob)
  Skipping contrib/automation/hgautomation/aws.py it has no-che?k-code (glob)
  Skipping contrib/automation/hgautomation/cli.py it has no-che?k-code (glob)
  Skipping contrib/automation/hgautomation/windows.py it has no-che?k-code (glob)
  Skipping contrib/automation/hgautomation/winrm.py it has no-che?k-code (glob)
  Skipping contrib/packaging/hgpackaging/downloads.py it has no-che?k-code (glob)
  Skipping contrib/packaging/hgpackaging/inno.py it has no-che?k-code (glob)
  Skipping contrib/packaging/hgpackaging/py2exe.py it has no-che?k-code (glob)
  Skipping contrib/packaging/hgpackaging/util.py it has no-che?k-code (glob)
  Skipping contrib/packaging/hgpackaging/wix.py it has no-che?k-code (glob)
  Skipping contrib/packaging/inno/build.py it has no-che?k-code (glob)
  Skipping contrib/packaging/wix/build.py it has no-che?k-code (glob)
  Skipping i18n/polib.py it has no-che?k-code (glob)
  Skipping mercurial/statprof.py it has no-che?k-code (glob)
  Skipping tests/badserverext.py it has no-che?k-code (glob)

@commands in debugcommands.py should be in alphabetical order.

  >>> import re
  >>> commands = []
  >>> with open('mercurial/debugcommands.py', 'rb') as fh:
  ...     for line in fh:
  ...         m = re.match(br"^@command\('([a-z]+)", line)
  ...         if m:
  ...             commands.append(m.group(1))
  >>> scommands = list(sorted(commands))
  >>> for i, command in enumerate(scommands):
  ...     if command != commands[i]:
  ...         print('commands in debugcommands.py not sorted; first differing '
  ...               'command is %s; expected %s' % (commands[i], command))
  ...         break

Prevent adding new files in the root directory accidentally.

  $ testrepohg files 'glob:*'
  .arcconfig
  .clang-format
  .editorconfig
  .hgignore
  .hgsigs
  .hgtags
  .jshintrc
  CONTRIBUTING
  CONTRIBUTORS
  COPYING
  Makefile
  README.rst
  hg
  hgeditor
  hgweb.cgi
  setup.py

Prevent adding modules which could be shadowed by ancient .so/.dylib.

  $ testrepohg files \
  > mercurial/base85.py \
  > mercurial/bdiff.py \
  > mercurial/diffhelpers.py \
  > mercurial/mpatch.py \
  > mercurial/osutil.py \
  > mercurial/parsers.py \
  > mercurial/zstd.py
  [1]

Keep python3 tests sorted:
  $ sort < contrib/python3-whitelist > $TESTTMP/py3sorted
  $ cmp contrib/python3-whitelist $TESTTMP/py3sorted || echo 'Please sort passing tests!'