hghave: wrap command output matching

tests/hghave

@@ -1,115 +1,123 b''
 #!/usr/bin/env python
 """Test the running system for features availability. Exit with zero
 if all features are there, non-zero otherwise. If a feature name is
 prefixed with "no-", the absence of feature is tested.
 """
 import optparse
 import os
+import re
 import sys
 import tempfile
 
 tempprefix = 'hg-hghave-'
 
+def matchoutput(cmd, regexp):
+    """Return True if cmd executes successfully and its output
+    is matched by the supplied regular expression.
+    """
+    r = re.compile(regexp)
+    fh = os.popen(cmd)
+    s = fh.read()
+    ret = fh.close()
+    return ret is None and r.search(s)
+
 def has_symlink():
     return hasattr(os, "symlink")
 
 def has_fifo():
     return hasattr(os, "mkfifo")
 
 def has_executablebit():
     fd, path = tempfile.mkstemp(prefix=tempprefix)
     os.close(fd)
     try:
         s = os.lstat(path).st_mode
         os.chmod(path, s | 0100)
         return (os.lstat(path).st_mode & 0100 != 0)
     finally:
         os.remove(path)
 
 def has_eol_in_paths():
     try:
         fd, path = tempfile.mkstemp(prefix=tempprefix, suffix='\n\r')
         os.close(fd)
         os.remove(path)
         return True
     except:
         return False
 
 def has_hotshot():
     try:
         # hotshot.stats tests hotshot and many problematic dependencies
         # like profile.
         import hotshot.stats
         return True
     except ImportError:
         return False
 
 def has_lsprof():
     try:
         import _lsprof
         return True
     except ImportError:
         return False
 
 def has_git():
-    fh = os.popen('git --version 2>&1')
-    s = fh.read()
-    ret = fh.close()
-    return ret is None and s.startswith('git version')
+    return matchoutput('git --version 2>&1', r'^git version')
 
 checks = {
     "eol-in-paths": (has_eol_in_paths, "end-of-lines in paths"),
     "execbit": (has_executablebit, "executable bit"),
     "git": (has_git, "git command line client"),
     "fifo": (has_fifo, "named pipes"),
     "hotshot": (has_hotshot, "python hotshot module"),
     "lsprof": (has_lsprof, "python lsprof module"),
     "symlink": (has_symlink, "symbolic links"),
 }
 
 def list_features():
     for name, feature in checks.iteritems():
         desc = feature[1]
         print name + ':', desc
 
 parser = optparse.OptionParser("%prog [options] [features]")
 parser.add_option("--list-features", action="store_true",
                   help="list available features")
 parser.add_option("-q", "--quiet", action="store_true",
                   help="check features silently")
 
 if __name__ == '__main__':
     options, args = parser.parse_args()
     if options.list_features:
         list_features()
         sys.exit(0)
 
     quiet = options.quiet
 
     failures = 0
 
     def error(msg):
         global failures
         if not quiet:
             sys.stderr.write(msg + '\n')
         failures += 1
 
     for feature in args:
         negate = feature.startswith('no-')
         if negate:
             feature = feature[3:]
 
         if feature not in checks:
             error('hghave: unknown feature: ' + feature)
             continue
 
         check, desc = checks[feature]
         if not negate and not check():
             error('hghave: missing feature: ' + desc)
         elif negate and check():
             error('hghave: system supports %s' % desc)
 
     if failures != 0:
         sys.exit(1)