run-tests: Pass arguments into argument parser

Before, arguments were not passed into the optparse.OptionParser
instance and were coming from sys.argv. This patch enables consumers to
define the list of arguments to parse without having to adjust sys.argv.

tests/run-tests.py

@@ -133,7 +133,7 b' def parselistfiles(files, listtype, warn'
         f.close()
     return entries
 
-def parseargs():
+def parseargs(args):
     parser = optparse.OptionParser("%prog [options] [tests]")
 
     # keep these sorted
@@ -210,7 +210,7 b' def parseargs():'
     for option, (envvar, default) in defaults.items():
         defaults[option] = type(default)(os.environ.get(envvar, default))
     parser.set_defaults(**defaults)
-    (options, args) = parser.parse_args()
+    (options, args) = parser.parse_args(args)
 
     # jython is always pure
     if 'java' in sys.platform or '__pypy__' in sys.modules:
@@ -1176,8 +1176,8 b' def runtests(options, tests):'
 testtypes = [('.py', pytest, '.out'),
              ('.t', tsttest, '')]
 
-def main():
-    (options, args) = parseargs()
+def main(args):
+    (options, args) = parseargs(args)
     os.umask(022)
 
     checktools()
@@ -1299,4 +1299,4 b' def main():'
         cleanup(options)
 
 if __name__ == '__main__':
-    main()
+    main(sys.argv[1:])