tests: execute check-config.py without xargs

Before this patch, test-check-config.t fails on Solaris, because
"xargs" doesn't invoke check-config.py with all filenames at once.

"xargs" may invoke specified command multiple times with part of
arguments given from stdin: according to "xargs(1)" man page, this
dividing arguments is system-dependent.

For portability of test-check-config.t, this patch adds "xargs" like
mode to check-config.py and executes it in test-check-config.t without
"xargs".

contrib/check-config.py

@@ -1,108 +1,111 b''
 #!/usr/bin/env python
 #
 # check-config - a config flag documentation checker for Mercurial
 #
 # Copyright 2015 Matt Mackall <[e-mail]>
 #
 # This software may be used and distributed according to the terms of the
 # GNU General Public License version 2 or any later version.
 
 import re
 import sys
 
 foundopts = {}
 documented = {}
 
 configre = (r"""ui\.config(|int|bool|list)\(['"](\S+)['"],\s*"""
             r"""['"](\S+)['"](,\s+(?:default=)?(\S+?))?\)""")
 configpartialre = (r"""ui\.config""")
 
 def main(args):
     for f in args:
         sect = ''
         prevname = ''
         confsect = ''
         carryover = ''
         for l in open(f):
 
             # check topic-like bits
             m = re.match('\s*``(\S+)``', l)
             if m:
                 prevname = m.group(1)
             if re.match('^\s*-+$', l):
                 sect = prevname
                 prevname = ''
 
             if sect and prevname:
                 name = sect + '.' + prevname
                 documented[name] = 1
 
             # check docstring bits
             m = re.match(r'^\s+\[(\S+)\]', l)
             if m:
                 confsect = m.group(1)
                 continue
             m = re.match(r'^\s+(?:#\s*)?(\S+) = ', l)
             if m:
                 name = confsect + '.' + m.group(1)
                 documented[name] = 1
 
             # like the bugzilla extension
             m = re.match(r'^\s*(\S+\.\S+)$', l)
             if m:
                 documented[m.group(1)] = 1
 
             # like convert
             m = re.match(r'^\s*:(\S+\.\S+):\s+', l)
             if m:
                 documented[m.group(1)] = 1
 
             # quoted in help or docstrings
             m = re.match(r'.*?``(\S+\.\S+)``', l)
             if m:
                 documented[m.group(1)] = 1
 
             # look for ignore markers
             m = re.search(r'# (?:internal|experimental|deprecated|developer)'
                           ' config: (\S+\.\S+)$', l)
             if m:
                 documented[m.group(1)] = 1
 
             # look for code-like bits
             line = carryover + l
             m = re.search(configre, line, re.MULTILINE)
             if m:
                 ctype = m.group(1)
                 if not ctype:
                     ctype = 'str'
                 name = m.group(2) + "." + m.group(3)
                 default = m.group(5)
                 if default in (None, 'False', 'None', '0', '[]', '""', "''"):
                     default = ''
                 if re.match('[a-z.]+$', default):
                     default = '<variable>'
                 if name in foundopts and (ctype, default) != foundopts[name]:
                     print l
                     print "conflict on %s: %r != %r" % (name, (ctype, default),
                                                         foundopts[name])
                 foundopts[name] = (ctype, default)
                 carryover = ''
             else:
                 m = re.search(configpartialre, line)
                 if m:
                     carryover = line
                 else:
                     carryover = ''
 
     for name in sorted(foundopts):
         if name not in documented:
             if not (name.startswith("devel.") or
                     name.startswith("experimental.") or
                     name.startswith("debug.")):
                 ctype, default = foundopts[name]
                 if default:
                     default = ' [%s]' % default
                 print "undocumented: %s (%s)%s" % (name, ctype, default)
 
 if __name__ == "__main__":
-    sys.exit(main(sys.argv[1:]))
+    if len(sys.argv) > 1:
+        sys.exit(main(sys.argv[1:]))
+    else:
+        sys.exit(main([l.rstrip() for l in sys.stdin]))

tests/test-check-config.t

@@ -1,8 +1,8 b''
 #require test-repo
 
   $ cd "$TESTDIR"/..
 
 New errors are not allowed. Warnings are strongly discouraged.
 
   $ hg files "set:(**.py or **.txt) - tests/**" | sed 's|\\|/|g' |
-  >   xargs python contrib/check-config.py
+  >   python contrib/check-config.py