text: """Supporting definitions for the Python regression tests."""
  
  if __name__ != 'test.test_support':
      raise ImportError('test_support must be imported from the test package')
  
  import contextlib
  import errno
  import functools
  import gc
  import socket
  import sys
  import os
  import platform
  import shutil
  import warnings
  import unittest
  import importlib
  import UserDict
  import re
  import time
  try:
      import thread
  except ImportError:
      thread = None
  
  __all__ = ["Error", "TestFailed", "ResourceDenied", "import_module",
             "verbose", "use_resources", "max_memuse", "record_original_stdout",
             "get_original_stdout", "unload", "unlink", "rmtree", "forget",
             "is_resource_enabled", "requires", "find_unused_port", "bind_port",
             "fcmp", "have_unicode", "is_jython", "TESTFN", "HOST", "FUZZ",
             "SAVEDCWD", "temp_cwd", "findfile", "sortdict", "check_syntax_error",
             "open_urlresource", "check_warnings", "check_py3k_warnings",
             "CleanImport", "EnvironmentVarGuard", "captured_output",
             "captured_stdout", "TransientResource", "transient_internet",
             "run_with_locale", "set_memlimit", "bigmemtest", "bigaddrspacetest",
             "BasicTestRunner", "run_unittest", "run_doctest", "threading_setup",
             "threading_cleanup", "reap_children", "cpython_only",
             "check_impl_detail", "get_attribute", "py3k_bytes",
             "import_fresh_module", "threading_cleanup", "reap_children",
             "strip_python_stderr"]
  
  class Error(Exception):
      """Base class for regression test exceptions."""
  
  class TestFailed(Error):
      """Test failed."""
  
  class ResourceDenied(unittest.SkipTest):
      """Test skipped because it requested a disallowed resource.
  
      This is raised when a test calls requires() for a resource that
      has not been enabled.  It is used to distinguish between expected
      and unexpected skips.
      """
  
  @contextlib.contextmanager
  def _ignore_deprecated_imports(ignore=True):
      """Context manager to suppress package and module deprecation
      warnings when importing them.
  
      If ignore is False, this context manager has no effect."""
      if ignore:
          with warnings.catch_warnings():
              warnings.filterwarnings("ignore", ".+ (module|package)",
                                      DeprecationWarning)
              yield
      else:
          yield
  
  
  def import_module(name, deprecated=False):
      """Import and return the module to be tested, raising SkipTest if
      it is not available.
  
      If deprecated is True, any module or package deprecation messages
      will be suppressed."""
      with _ignore_deprecated_imports(deprecated):
          try:
              return importlib.import_module(name)
          except ImportError, msg:
              raise unittest.SkipTest(str(msg))
  
  
  def _save_and_remove_module(name, orig_modules):
      """Helper function to save and remove a module from sys.modules
  
         Raise ImportError if the module can't be imported."""
      # try to import the module and raise an error if it can't be imported
      if name not in sys.modules:
          __import__(name)
          del sys.modules[name]
      for modname in list(sys.modules):
          if modname == name or modname.startswith(name + '.'):
              orig_modules[modname] = sys.modules[modname]
              del sys.modules[modname]
  
  def _save_and_block_module(name, orig_modules):
      """Helper function to save and block a module in sys.modules
  
         Return True if the module was in sys.modules, False otherwise."""
      saved = True
      try:
          orig_modules[name] = sys.modules[name]
      except KeyError:
          saved = False
      sys.modules[name] = None
      return saved
  
  
  def import_fresh_module(name, fresh=(), blocked=(), deprecated=False):
      """Imports and returns a module, deliberately bypassing the sys.modules cache
      and importing a fresh copy of the module. Once the import is complete,
      the sys.modules cache is restored to its original state.
  
      Modules named in fresh are also imported anew if needed by the import.
      If one of these modules can't be imported, None is returned.
  
      Importing of modules named in blocked is prevented while the fresh import
      takes place.
  
      If deprecated is True, any module or package deprecation messages
      will be suppressed."""
      # NOTE: test_heapq, test_json, and test_warnings include extra sanity
      # checks to make sure that this utility function is working as expected
      with _ignore_deprecated_imports(deprecated):
          # Keep track of modules saved for later restoration as well
          # as those which just need a blocking entry removed
          orig_modules = {}
          names_to_remove = []
          _save_and_remove_module(name, orig_modules)
          try:
              for fresh_name in fresh:
                  _save_and_remove_module(fresh_name, orig_modules)
              for blocked_name in blocked:
                  if not _save_and_block_module(blocked_name, orig_modules):
                      names_to_remove.append(blocked_name)
              fresh_module = importlib.import_module(name)
          except ImportError:
              fresh_module = None
          finally:
              for orig_name, module in orig_modules.items():
                  sys.modules[orig_name] = module
              for name_to_remove in names_to_remove:
                  del sys.modules[name_to_remove]
          return fresh_module
  
  
  def get_attribute(obj, name):
      """Get an attribute, raising SkipTest if AttributeError is raised."""
      try:
          attribute = getattr(obj, name)
      except AttributeError:
          raise unittest.SkipTest("module %s has no attribute %s" % (
              obj.__name__, name))
      else:
          return attribute
  
  
  verbose = 1              # Flag set to 0 by regrtest.py
  use_resources = None     # Flag set to [] by regrtest.py
  max_memuse = 0           # Disable bigmem tests (they will still be run with
                           # small sizes, to make sure they work.)
  real_max_memuse = 0
  
  # _original_stdout is meant to hold stdout at the time regrtest began.
  # This may be "the real" stdout, or IDLE's emulation of stdout, or whatever.
  # The point is to have some flavor of stdout the user can actually see.
  _original_stdout = None
  def record_original_stdout(stdout):
      global _original_stdout
      _original_stdout = stdout
  
  def get_original_stdout():
      return _original_stdout or sys.stdout
  
  def unload(name):
      try:
          del sys.modules[name]
      except KeyError:
          pass
  
  def unlink(filename):
      try:
          os.unlink(filename)
      except OSError:
          pass
  
  def rmtree(path):
      try:
          shutil.rmtree(path)
      except OSError, e:
          # Unix returns ENOENT, Windows returns ESRCH.
          if e.errno not in (errno.ENOENT, errno.ESRCH):
              raise
  
  def forget(modname):
      '''"Forget" a module was ever imported by removing it from sys.modules and
      deleting any .pyc and .pyo files.'''
      unload(modname)
      for dirname in sys.path:
          unlink(os.path.join(dirname, modname + os.extsep + 'pyc'))
          # Deleting the .pyo file cannot be within the 'try' for the .pyc since
          # the chance exists that there is no .pyc (and thus the 'try' statement
          # is exited) but there is a .pyo file.
          unlink(os.path.join(dirname, modname + os.extsep + 'pyo'))
  
  def is_resource_enabled(resource):
      """Test whether a resource is enabled.  Known resources are set by
      regrtest.py."""
      return use_resources is not None and resource in use_resources
  
  def requires(resource, msg=None):
      """Raise ResourceDenied if the specified resource is not available.
  
      If the caller's module is __main__ then automatically return True.  The
      possibility of False being returned occurs when regrtest.py is executing."""
      # see if the caller's module is __main__ - if so, treat as if
      # the resource was set
      if sys._getframe(1).f_globals.get("__name__") == "__main__":
          return
      if not is_resource_enabled(resource):
          if msg is None:
              msg = "Use of the `%s' resource not enabled" % resource
          raise ResourceDenied(msg)
  
  HOST = 'localhost'
  
  def find_unused_port(family=socket.AF_INET, socktype=socket.SOCK_STREAM):
      """Returns an unused port that should be suitable for binding.  This is
      achieved by creating a temporary socket with the same family and type as
      the 'sock' parameter (default is AF_INET, SOCK_STREAM), and binding it to
      the specified host address (defaults to 0.0.0.0) with the port set to 0,
      eliciting an unused ephemeral port from the OS.  The temporary socket is
      then closed and deleted, and the ephemeral port is returned.
  
      Either this method or bind_port() should be used for any tests where a
      server socket needs to be bound to a particular port for the duration of
      the test.  Which one to use depends on whether the calling code is creating
      a python socket, or if an unused port needs to be provided in a constructor
      or passed to an external program (i.e. the -accept argument to openssl's
      s_server mode).  Always prefer bind_port() over find_unused_port() where
      possible.  Hard coded ports should *NEVER* be used.  As soon as a server
      socket is bound to a hard coded port, the ability to run multiple instances
      of the test simultaneously on the same host is compromised, which makes the
      test a ticking time bomb in a buildbot environment. On Unix buildbots, this
      may simply manifest as a failed test, which can be recovered from without
      intervention in most cases, but on Windows, the entire python process can
      completely and utterly wedge, requiring someone to log in to the buildbot
      and manually kill the affected process.
  
      (This is easy to reproduce on Windows, unfortunately, and can be traced to
      the SO_REUSEADDR socket option having different semantics on Windows versus
      Unix/Linux.  On Unix, you can't have two AF_INET SOCK_STREAM sockets bind,
      listen and then accept connections on identical host/ports.  An EADDRINUSE
      socket.error will be raised at some point (depending on the platform and
      the order bind and listen were called on each socket).
  
      However, on Windows, if SO_REUSEADDR is set on the sockets, no EADDRINUSE
      will ever be raised when attempting to bind two identical host/ports. When
      accept() is called on each socket, the second caller's process will steal
      the port from the first caller, leaving them both in an awkwardly wedged
      state where they'll no longer respond to any signals or graceful kills, and
      must be forcibly killed via OpenProcess()/TerminateProcess().
  
      The solution on Windows is to use the SO_EXCLUSIVEADDRUSE socket option
      instead of SO_REUSEADDR, which effectively affords the same semantics as
      SO_REUSEADDR on Unix.  Given the propensity of Unix developers in the Open
      Source world compared to Windows ones, this is a common mistake.  A quick
      look over OpenSSL's 0.9.8g source shows that they use SO_REUSEADDR when
      openssl.exe is called with the 's_server' option, for example. See
      http://bugs.python.org/issue2550 for more info.  The following site also
      has a very thorough description about the implications of both REUSEADDR
      and EXCLUSIVEADDRUSE on Windows:
      http://msdn2.microsoft.com/en-us/library/ms740621(VS.85).aspx)
  
      XXX: although this approach is a vast improvement on previous attempts to
      elicit unused ports, it rests heavily on the assumption that the ephemeral
      port returned to us by the OS won't immediately be dished back out to some
      other process when we close and delete our temporary socket but before our
      calling code has a chance to bind the returned port.  We can deal with this
      issue if/when we come across it."""
      tempsock = socket.socket(family, socktype)
      port = bind_port(tempsock)
      tempsock.close()
      del tempsock
      return port
  
  def bind_port(sock, host=HOST):
      """Bind the socket to a free port and return the port number.  Relies on
      ephemeral ports in order to ensure we are using an unbound port.  This is
      important as many tests may be running simultaneously, especially in a
      buildbot environment.  This method raises an exception if the sock.family
      is AF_INET and sock.type is SOCK_STREAM, *and* the socket has SO_REUSEADDR
      or SO_REUSEPORT set on it.  Tests should *never* set these socket options
      for TCP/IP sockets.  The only case for setting these options is testing
      multicasting via multiple UDP sockets.
  
      Additionally, if the SO_EXCLUSIVEADDRUSE socket option is available (i.e.
      on Windows), it will be set on the socket.  This will prevent anyone else
      from bind()'ing to our host/port for the duration of the test.
      """
      if sock.family == socket.AF_INET and sock.type == socket.SOCK_STREAM:
          if hasattr(socket, 'SO_REUSEADDR'):
              if sock.getsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR) == 1:
                  raise TestFailed("tests should never set the SO_REUSEADDR "   \
                                   "socket option on TCP/IP sockets!")
          if hasattr(socket, 'SO_REUSEPORT'):
              if sock.getsockopt(socket.SOL_SOCKET, socket.SO_REUSEPORT) == 1:
                  raise TestFailed("tests should never set the SO_REUSEPORT "   \
                                   "socket option on TCP/IP sockets!")
          if hasattr(socket, 'SO_EXCLUSIVEADDRUSE'):
              sock.setsockopt(socket.SOL_SOCKET, socket.SO_EXCLUSIVEADDRUSE, 1)
  
      sock.bind((host, 0))
      port = sock.getsockname()[1]
      return port
  
  FUZZ = 1e-6
  
  def fcmp(x, y): # fuzzy comparison function
      if isinstance(x, float) or isinstance(y, float):
          try:
              fuzz = (abs(x) + abs(y)) * FUZZ
              if abs(x-y) <= fuzz:
                  return 0
          except:
              pass
      elif type(x) == type(y) and isinstance(x, (tuple, list)):
          for i in range(min(len(x), len(y))):
              outcome = fcmp(x[i], y[i])
              if outcome != 0:
                  return outcome
          return (len(x) > len(y)) - (len(x) < len(y))
      return (x > y) - (x < y)
  
  try:
      unicode
      have_unicode = True
  except NameError:
      have_unicode = False
  
  is_jython = sys.platform.startswith('java')
  
  # Filename used for testing
  if os.name == 'java':
      # Jython disallows @ in module names
      TESTFN = '$test'
  elif os.name == 'riscos':
      TESTFN = 'testfile'
  else:
      TESTFN = '@test'
      # Unicode name only used if TEST_FN_ENCODING exists for the platform.
      if have_unicode:
          # Assuming sys.getfilesystemencoding()!=sys.getdefaultencoding()
          # TESTFN_UNICODE is a filename that can be encoded using the
          # file system encoding, but *not* with the default (ascii) encoding
          if isinstance('', unicode):
              # python -U
              # XXX perhaps unicode() should accept Unicode strings?
              TESTFN_UNICODE = "@test-\xe0\xf2"
          else:
              # 2 latin characters.
              TESTFN_UNICODE = unicode("@test-\xe0\xf2", "latin-1")
          TESTFN_ENCODING = sys.getfilesystemencoding()
          # TESTFN_UNENCODABLE is a filename that should *not* be
          # able to be encoded by *either* the default or filesystem encoding.
          # This test really only makes sense on Windows NT platforms
          # which have special Unicode support in posixmodule.
          if (not hasattr(sys, "getwindowsversion") or
                  sys.getwindowsversion()[3] < 2): #  0=win32s or 1=9x/ME
              TESTFN_UNENCODABLE = None
          else:
              # Japanese characters (I think - from bug 846133)
              TESTFN_UNENCODABLE = eval('u"@test-\u5171\u6709\u3055\u308c\u308b"')
              try:
                  # XXX - Note - should be using TESTFN_ENCODING here - but for
                  # Windows, "mbcs" currently always operates as if in
                  # errors=ignore' mode - hence we get '?' characters rather than
                  # the exception.  'Latin1' operates as we expect - ie, fails.
                  # See [ 850997 ] mbcs encoding ignores errors
                  TESTFN_UNENCODABLE.encode("Latin1")
              except UnicodeEncodeError:
                  pass
              else:
                  print \
                  'WARNING: The filename %r CAN be encoded by the filesystem.  ' \
                  'Unicode filename tests may not be effective' \
                  % TESTFN_UNENCODABLE
  
  
  # Disambiguate TESTFN for parallel testing, while letting it remain a valid
  # module name.
  TESTFN = "{}_{}_tmp".format(TESTFN, os.getpid())
  
  # Save the initial cwd
  SAVEDCWD = os.getcwd()
  
  @contextlib.contextmanager
  def temp_cwd(name='tempcwd', quiet=False):
      """
      Context manager that creates a temporary directory and set it as CWD.
  
      The new CWD is created in the current directory and it's named *name*.
      If *quiet* is False (default) and it's not possible to create or change
      the CWD, an error is raised.  If it's True, only a warning is raised
      and the original CWD is used.
      """
      if isinstance(name, unicode):
          try:
              name = name.encode(sys.getfilesystemencoding() or 'ascii')
          except UnicodeEncodeError:
              if not quiet:
                  raise unittest.SkipTest('unable to encode the cwd name with '
                                          'the filesystem encoding.')
      saved_dir = os.getcwd()
      is_temporary = False
      try:
          os.mkdir(name)
          os.chdir(name)
          is_temporary = True
      except OSError:
          if not quiet:
              raise
          warnings.warn('tests may fail, unable to change the CWD to ' + name,
                        RuntimeWarning, stacklevel=3)
      try:
          yield os.getcwd()
      finally:
          os.chdir(saved_dir)
          if is_temporary:
              rmtree(name)
  
  
  def findfile(file, here=None, subdir=None):
      """Try to find a file on sys.path and the working directory.  If it is not
      found the argument passed to the function is returned (this does not
      necessarily signal failure; could still be the legitimate path)."""
      import test
      if os.path.isabs(file):
          return file
      if subdir is not None:
          file = os.path.join(subdir, file)
      path = sys.path
      if here is None:
          path = test.__path__ + path
      else:
          path = [os.path.dirname(here)] + path
      for dn in path:
          fn = os.path.join(dn, file)
          if os.path.exists(fn): return fn
      return file
  
  def sortdict(dict):
      "Like repr(dict), but in sorted order."
      items = dict.items()
      items.sort()
      reprpairs = ["%r: %r" % pair for pair in items]
      withcommas = ", ".join(reprpairs)
      return "{%s}" % withcommas
  
  def make_bad_fd():
      """
      Create an invalid file descriptor by opening and closing a file and return
      its fd.
      """
      file = open(TESTFN, "wb")
      try:
          return file.fileno()
      finally:
          file.close()
          unlink(TESTFN)
  
  def check_syntax_error(testcase, statement):
      testcase.assertRaises(SyntaxError, compile, statement,
                            '<test string>', 'exec')
  
  def open_urlresource(url, check=None):
      import urlparse, urllib2
  
      filename = urlparse.urlparse(url)[2].split('/')[-1] # '/': it's URL!
  
      fn = os.path.join(os.path.dirname(__file__), "data", filename)
  
      def check_valid_file(fn):
          f = open(fn)
          if check is None:
              return f
          elif check(f):
              f.seek(0)
              return f
          f.close()
  
      if os.path.exists(fn):
          f = check_valid_file(fn)
          if f is not None:
              return f
          unlink(fn)
  
      # Verify the requirement before downloading the file
      requires('urlfetch')
  
      print >> get_original_stdout(), '\tfetching %s ...' % url
      f = urllib2.urlopen(url, timeout=15)
      try:
          with open(fn, "wb") as out:
              s = f.read()
              while s:
                  out.write(s)
                  s = f.read()
      finally:
          f.close()
  
      f = check_valid_file(fn)
      if f is not None:
          return f
      raise TestFailed('invalid resource "%s"' % fn)
  
  
  class WarningsRecorder(object):
      """Convenience wrapper for the warnings list returned on
         entry to the warnings.catch_warnings() context manager.
      """
      def __init__(self, warnings_list):
          self._warnings = warnings_list
          self._last = 0
  
      def __getattr__(self, attr):
          if len(self._warnings) > self._last:
              return getattr(self._warnings[-1], attr)
          elif attr in warnings.WarningMessage._WARNING_DETAILS:
              return None
          raise AttributeError("%r has no attribute %r" % (self, attr))
  
      @property
      def warnings(self):
          return self._warnings[self._last:]
  
      def reset(self):
          self._last = len(self._warnings)
  
  
  def _filterwarnings(filters, quiet=False):
      """Catch the warnings, then check if all the expected
      warnings have been raised and re-raise unexpected warnings.
      If 'quiet' is True, only re-raise the unexpected warnings.
      """
      # Clear the warning registry of the calling module
      # in order to re-raise the warnings.
      frame = sys._getframe(2)
      registry = frame.f_globals.get('__warningregistry__')
      if registry:
          registry.clear()
      with warnings.catch_warnings(record=True) as w:
          # Set filter "always" to record all warnings.  Because
          # test_warnings swap the module, we need to look up in
          # the sys.modules dictionary.
          sys.modules['warnings'].simplefilter("always")
          yield WarningsRecorder(w)
      # Filter the recorded warnings
      reraise = [warning.message for warning in w]
      missing = []
      for msg, cat in filters:
          seen = False
          for exc in reraise[:]:
              message = str(exc)
              # Filter out the matching messages
              if (re.match(msg, message, re.I) and
                  issubclass(exc.__class__, cat)):
                  seen = True
                  reraise.remove(exc)
          if not seen and not quiet:
              # This filter caught nothing
              missing.append((msg, cat.__name__))
      if reraise:
          raise AssertionError("unhandled warning %r" % reraise[0])
      if missing:
          raise AssertionError("filter (%r, %s) did not catch any warning" %
                               missing[0])
  
  
  @contextlib.contextmanager
  def check_warnings(*filters, **kwargs):
      """Context manager to silence warnings.
  
      Accept 2-tuples as positional arguments:
          ("message regexp", WarningCategory)
  
      Optional argument:
       - if 'quiet' is True, it does not fail if a filter catches nothing
          (default True without argument,
           default False if some filters are defined)
  
      Without argument, it defaults to:
          check_warnings(("", Warning), quiet=True)
      """
      quiet = kwargs.get('quiet')
      if not filters:
          filters = (("", Warning),)
          # Preserve backward compatibility
          if quiet is None:
              quiet = True
      return _filterwarnings(filters, quiet)
  
  
  @contextlib.contextmanager
  def check_py3k_warnings(*filters, **kwargs):
      """Context manager to silence py3k warnings.
  
      Accept 2-tuples as positional arguments:
          ("message regexp", WarningCategory)
  
      Optional argument:
       - if 'quiet' is True, it does not fail if a filter catches nothing
          (default False)
  
      Without argument, it defaults to:
          check_py3k_warnings(("", DeprecationWarning), quiet=False)
      """
      if sys.py3kwarning:
          if not filters:
              filters = (("", DeprecationWarning),)
      else:
          # It should not raise any py3k warning
          filters = ()
      return _filterwarnings(filters, kwargs.get('quiet'))
  
  
  class CleanImport(object):
      """Context manager to force import to return a new module reference.
  
      This is useful for testing module-level behaviours, such as
      the emission of a DeprecationWarning on import.
  
      Use like this:
  
          with CleanImport("foo"):
              importlib.import_module("foo") # new reference
      """
  
      def __init__(self, *module_names):
          self.original_modules = sys.modules.copy()
          for module_name in module_names:
              if module_name in sys.modules:
                  module = sys.modules[module_name]
                  # It is possible that module_name is just an alias for
                  # another module (e.g. stub for modules renamed in 3.x).
                  # In that case, we also need delete the real module to clear
                  # the import cache.
                  if module.__name__ != module_name:
                      del sys.modules[module.__name__]
                  del sys.modules[module_name]
  
      def __enter__(self):
          return self
  
      def __exit__(self, *ignore_exc):
          sys.modules.update(self.original_modules)
  
  
  class EnvironmentVarGuard(UserDict.DictMixin):
  
      """Class to help protect the environment variable properly.  Can be used as
      a context manager."""
  
      def __init__(self):
          self._environ = os.environ
          self._changed = {}
  
      def __getitem__(self, envvar):
          return self._environ[envvar]
  
      def __setitem__(self, envvar, value):
          # Remember the initial value on the first access
          if envvar not in self._changed:
              self._changed[envvar] = self._environ.get(envvar)
          self._environ[envvar] = value
  
      def __delitem__(self, envvar):
          # Remember the initial value on the first access
          if envvar not in self._changed:
              self._changed[envvar] = self._environ.get(envvar)
          if envvar in self._environ:
              del self._environ[envvar]
  
      def keys(self):
          return self._environ.keys()
  
      def set(self, envvar, value):
          self[envvar] = value
  
      def unset(self, envvar):
          del self[envvar]
  
      def __enter__(self):
          return self
  
      def __exit__(self, *ignore_exc):
          for (k, v) in self._changed.items():
              if v is None:
                  if k in self._environ:
                      del self._environ[k]
              else:
                  self._environ[k] = v
          os.environ = self._environ
  
  
  class DirsOnSysPath(object):
      """Context manager to temporarily add directories to sys.path.
  
      This makes a copy of sys.path, appends any directories given
      as positional arguments, then reverts sys.path to the copied
      settings when the context ends.
  
      Note that *all* sys.path modifications in the body of the
      context manager, including replacement of the object,
      will be reverted at the end of the block.
      """
  
      def __init__(self, *paths):
          self.original_value = sys.path[:]
          self.original_object = sys.path
          sys.path.extend(paths)
  
      def __enter__(self):
          return self
  
      def __exit__(self, *ignore_exc):
          sys.path = self.original_object
          sys.path[:] = self.original_value
  
  
  class TransientResource(object):
  
      """Raise ResourceDenied if an exception is raised while the context manager
      is in effect that matches the specified exception and attributes."""
  
      def __init__(self, exc, **kwargs):
          self.exc = exc
          self.attrs = kwargs
  
      def __enter__(self):
          return self
  
      def __exit__(self, type_=None, value=None, traceback=None):
          """If type_ is a subclass of self.exc and value has attributes matching
          self.attrs, raise ResourceDenied.  Otherwise let the exception
          propagate (if any)."""
          if type_ is not None and issubclass(self.exc, type_):
              for attr, attr_value in self.attrs.iteritems():
                  if not hasattr(value, attr):
                      break
                  if getattr(value, attr) != attr_value:
                      break
              else:
                  raise ResourceDenied("an optional resource is not available")
  
  
  @contextlib.contextmanager
  def transient_internet(resource_name, timeout=30.0, errnos=()):
      """Return a context manager that raises ResourceDenied when various issues
      with the Internet connection manifest themselves as exceptions."""
      default_errnos = [
          ('ECONNREFUSED', 111),
          ('ECONNRESET', 104),
          ('EHOSTUNREACH', 113),
          ('ENETUNREACH', 101),
          ('ETIMEDOUT', 110),
      ]
      default_gai_errnos = [
          ('EAI_AGAIN', -3),
          ('EAI_FAIL', -4),
          ('EAI_NONAME', -2),
          ('EAI_NODATA', -5),
      ]
  
      denied = ResourceDenied("Resource '%s' is not available" % resource_name)
      captured_errnos = errnos
      gai_errnos = []
      if not captured_errnos:
          captured_errnos = [getattr(errno, name, num)
                             for (name, num) in default_errnos]
          gai_errnos = [getattr(socket, name, num)
                        for (name, num) in default_gai_errnos]
  
      def filter_error(err):
          n = getattr(err, 'errno', None)
          if (isinstance(err, socket.timeout) or
              (isinstance(err, socket.gaierror) and n in gai_errnos) or
              n in captured_errnos):
              if not verbose:
                  sys.stderr.write(denied.args[0] + "\n")
              raise denied
  
      old_timeout = socket.getdefaulttimeout()
      try:
          if timeout is not None:
              socket.setdefaulttimeout(timeout)
          yield
      except IOError as err:
          # urllib can wrap original socket errors multiple times (!), we must
          # unwrap to get at the original error.
          while True:
              a = err.args
              if len(a) >= 1 and isinstance(a[0], IOError):
                  err = a[0]
              # The error can also be wrapped as args[1]:
              #    except socket.error as msg:
              #        raise IOError('socket error', msg).with_traceback(sys.exc_info()[2])
              elif len(a) >= 2 and isinstance(a[1], IOError):
                  err = a[1]
              else:
                  break
          filter_error(err)
          raise
      # XXX should we catch generic exceptions and look for their
      # __cause__ or __context__?
      finally:
          socket.setdefaulttimeout(old_timeout)
  
  
  @contextlib.contextmanager
  def captured_output(stream_name):
      """Return a context manager used by captured_stdout and captured_stdin
      that temporarily replaces the sys stream *stream_name* with a StringIO."""
      import StringIO
      orig_stdout = getattr(sys, stream_name)
      setattr(sys, stream_name, StringIO.StringIO())
      try:
          yield getattr(sys, stream_name)
      finally:
          setattr(sys, stream_name, orig_stdout)
  
  def captured_stdout():
      """Capture the output of sys.stdout:
  
         with captured_stdout() as s:
             print "hello"
         self.assertEqual(s.getvalue(), "hello")
      """
      return captured_output("stdout")
  
  def captured_stderr():
      return captured_output("stderr")
  
  def captured_stdin():
      return captured_output("stdin")
  
  def gc_collect():
      """Force as many objects as possible to be collected.
  
      In non-CPython implementations of Python, this is needed because timely
      deallocation is not guaranteed by the garbage collector.  (Even in CPython
      this can be the case in case of reference cycles.)  This means that __del__
      methods may be called later than expected and weakrefs may remain alive for
      longer than expected.  This function tries its best to force all garbage
      objects to disappear.
      """
      gc.collect()
      if is_jython:
          time.sleep(0.1)
      gc.collect()
      gc.collect()
  
  
  #=======================================================================
  # Decorator for running a function in a different locale, correctly resetting
  # it afterwards.
  
  def run_with_locale(catstr, *locales):
      def decorator(func):
          def inner(*args, **kwds):
              try:
                  import locale
                  category = getattr(locale, catstr)
                  orig_locale = locale.setlocale(category)
              except AttributeError:
                  # if the test author gives us an invalid category string
                  raise
              except:
                  # cannot retrieve original locale, so do nothing
                  locale = orig_locale = None
              else:
                  for loc in locales:
                      try:
                          locale.setlocale(category, loc)
                          break
                      except:
                          pass
  
              # now run the function, resetting the locale on exceptions
              try:
                  return func(*args, **kwds)
              finally:
                  if locale and orig_locale:
                      locale.setlocale(category, orig_locale)
          inner.func_name = func.func_name
          inner.__doc__ = func.__doc__
          return inner
      return decorator
  
  #=======================================================================
  # Big-memory-test support. Separate from 'resources' because memory use should be configurable.
  
  # Some handy shorthands. Note that these are used for byte-limits as well
  # as size-limits, in the various bigmem tests
  _1M = 1024*1024
  _1G = 1024 * _1M
  _2G = 2 * _1G
  _4G = 4 * _1G
  
  MAX_Py_ssize_t = sys.maxsize
  
  def set_memlimit(limit):
      global max_memuse
      global real_max_memuse
      sizes = {
          'k': 1024,
          'm': _1M,
          'g': _1G,
          't': 1024*_1G,
      }
      m = re.match(r'(\d+(\.\d+)?) (K|M|G|T)b?$', limit,
                   re.IGNORECASE | re.VERBOSE)
      if m is None:
          raise ValueError('Invalid memory limit %r' % (limit,))
      memlimit = int(float(m.group(1)) * sizes[m.group(3).lower()])
      real_max_memuse = memlimit
      if memlimit > MAX_Py_ssize_t:
          memlimit = MAX_Py_ssize_t
      if memlimit < _2G - 1:
          raise ValueError('Memory limit %r too low to be useful' % (limit,))
      max_memuse = memlimit
  
  def bigmemtest(minsize, memuse, overhead=5*_1M):
      """Decorator for bigmem tests.
  
      'minsize' is the minimum useful size for the test (in arbitrary,
      test-interpreted units.) 'memuse' is the number of 'bytes per size' for
      the test, or a good estimate of it. 'overhead' specifies fixed overhead,
      independent of the testsize, and defaults to 5Mb.
  
      The decorator tries to guess a good value for 'size' and passes it to
      the decorated test function. If minsize * memuse is more than the
      allowed memory use (as defined by max_memuse), the test is skipped.
      Otherwise, minsize is adjusted upward to use up to max_memuse.
      """
      def decorator(f):
          def wrapper(self):
              if not max_memuse:
                  # If max_memuse is 0 (the default),
                  # we still want to run the tests with size set to a few kb,
                  # to make sure they work. We still want to avoid using
                  # too much memory, though, but we do that noisily.
                  maxsize = 5147
                  self.assertFalse(maxsize * memuse + overhead > 20 * _1M)
              else:
                  maxsize = int((max_memuse - overhead) / memuse)
                  if maxsize < minsize:
                      # Really ought to print 'test skipped' or something
                      if verbose:
                          sys.stderr.write("Skipping %s because of memory "
                                           "constraint\n" % (f.__name__,))
                      return
                  # Try to keep some breathing room in memory use
                  maxsize = max(maxsize - 50 * _1M, minsize)
              return f(self, maxsize)
          wrapper.minsize = minsize
          wrapper.memuse = memuse
          wrapper.overhead = overhead
          return wrapper
      return decorator
  
  def precisionbigmemtest(size, memuse, overhead=5*_1M):
      def decorator(f):
          def wrapper(self):
              if not real_max_memuse:
                  maxsize = 5147
              else:
                  maxsize = size
  
                  if real_max_memuse and real_max_memuse < maxsize * memuse:
                      if verbose:
                          sys.stderr.write("Skipping %s because of memory "
                                           "constraint\n" % (f.__name__,))
                      return
  
              return f(self, maxsize)
          wrapper.size = size
          wrapper.memuse = memuse
          wrapper.overhead = overhead
          return wrapper
      return decorator
  
  def bigaddrspacetest(f):
      """Decorator for tests that fill the address space."""
      def wrapper(self):
          if max_memuse < MAX_Py_ssize_t:
              if verbose:
                  sys.stderr.write("Skipping %s because of memory "
                                   "constraint\n" % (f.__name__,))
          else:
              return f(self)
      return wrapper
  
  #=======================================================================
  # unittest integration.
  
  class BasicTestRunner:
      def run(self, test):
          result = unittest.TestResult()
          test(result)
          return result
  
  def _id(obj):
      return obj
  
  def requires_resource(resource):
      if is_resource_enabled(resource):
          return _id
      else:
          return unittest.skip("resource {0!r} is not enabled".format(resource))
  
  def cpython_only(test):
      """
      Decorator for tests only applicable on CPython.
      """
      return impl_detail(cpython=True)(test)
  
  def impl_detail(msg=None, **guards):
      if check_impl_detail(**guards):
          return _id
      if msg is None:
          guardnames, default = _parse_guards(guards)
          if default:
              msg = "implementation detail not available on {0}"
          else:
              msg = "implementation detail specific to {0}"
          guardnames = sorted(guardnames.keys())
          msg = msg.format(' or '.join(guardnames))
      return unittest.skip(msg)
  
  def _parse_guards(guards):
      # Returns a tuple ({platform_name: run_me}, default_value)
      if not guards:
          return ({'cpython': True}, False)
      is_true = guards.values()[0]
      assert guards.values() == [is_true] * len(guards)   # all True or all False
      return (guards, not is_true)
  
  # Use the following check to guard CPython's implementation-specific tests --
  # or to run them only on the implementation(s) guarded by the arguments.
  def check_impl_detail(**guards):
      """This function returns True or False depending on the host platform.
         Examples:
            if check_impl_detail():               # only on CPython (default)
            if check_impl_detail(jython=True):    # only on Jython
            if check_impl_detail(cpython=False):  # everywhere except on CPython
      """
      guards, default = _parse_guards(guards)
      return guards.get(platform.python_implementation().lower(), default)
  
  # ----------------------------------
  # PyPy extension: you can run::
  #     python ..../test_foo.py --pdb
  # to get a pdb prompt in case of exceptions
  
  ResultClass = unittest.TextTestRunner.resultclass
  
  class TestResultWithPdb(ResultClass):
  
      def addError(self, testcase, exc_info):
          ResultClass.addError(self, testcase, exc_info)
          if '--pdb' in sys.argv:
              import pdb, traceback
              traceback.print_tb(exc_info[2])
              pdb.post_mortem(exc_info[2])
  
  # ----------------------------------
  
  def _run_suite(suite):
      """Run tests from a unittest.TestSuite-derived class."""
      if verbose:
          runner = unittest.TextTestRunner(sys.stdout, verbosity=2,
                                           resultclass=TestResultWithPdb)
      else:
          runner = BasicTestRunner()
  
      result = runner.run(suite)
      if not result.wasSuccessful():
          if len(result.errors) == 1 and not result.failures:
              err = result.errors[0][1]
          elif len(result.failures) == 1 and not result.errors:
              err = result.failures[0][1]
          else:
              err = "multiple errors occurred"
              if not verbose:
                  err += "; run in verbose mode for details"
          raise TestFailed(err)
  
  # ----------------------------------
  # PyPy extension: you can run::
  #     python ..../test_foo.py --filter bar
  # to run only the test cases whose name contains bar
  
  def filter_maybe(suite):
      try:
          i = sys.argv.index('--filter')
          filter = sys.argv[i+1]
      except (ValueError, IndexError):
          return suite
      tests = []
      for test in linearize_suite(suite):
          if filter in test._testMethodName:
              tests.append(test)
      return unittest.TestSuite(tests)
  
  def linearize_suite(suite_or_test):
      try:
          it = iter(suite_or_test)
      except TypeError:
          yield suite_or_test
          return
      for subsuite in it:
          for item in linearize_suite(subsuite):
              yield item
  
  # ----------------------------------
  
  def run_unittest(*classes):
      """Run tests from unittest.TestCase-derived classes."""
      valid_types = (unittest.TestSuite, unittest.TestCase)
      suite = unittest.TestSuite()
      for cls in classes:
          if isinstance(cls, str):
              if cls in sys.modules:
                  suite.addTest(unittest.findTestCases(sys.modules[cls]))
              else:
                  raise ValueError("str arguments must be keys in sys.modules")
          elif isinstance(cls, valid_types):
              suite.addTest(cls)
          else:
              suite.addTest(unittest.makeSuite(cls))
      suite = filter_maybe(suite)
      _run_suite(suite)
  
  
  #=======================================================================
  # doctest driver.
  
  def run_doctest(module, verbosity=None):
      """Run doctest on the given module.  Return (#failures, #tests).
  
      If optional argument verbosity is not specified (or is None), pass
      test_support's belief about verbosity on to doctest.  Else doctest's
      usual behavior is used (it searches sys.argv for -v).
      """
  
      import doctest
  
      if verbosity is None:
          verbosity = verbose
      else:
          verbosity = None
  
      # Direct doctest output (normally just errors) to real stdout; doctest
      # output shouldn't be compared by regrtest.
      save_stdout = sys.stdout
      sys.stdout = get_original_stdout()
      try:
          f, t = doctest.testmod(module, verbose=verbosity)
          if f:
              raise TestFailed("%d of %d doctests failed" % (f, t))
      finally:
          sys.stdout = save_stdout
      if verbose:
          print 'doctest (%s) ... %d tests with zero failures' % (module.__name__, t)
      return f, t
  
  #=======================================================================
  # Threading support to prevent reporting refleaks when running regrtest.py -R
  
  # NOTE: we use thread._count() rather than threading.enumerate() (or the
  # moral equivalent thereof) because a threading.Thread object is still alive
  # until its __bootstrap() method has returned, even after it has been
  # unregistered from the threading module.
  # thread._count(), on the other hand, only gets decremented *after* the
  # __bootstrap() method has returned, which gives us reliable reference counts
  # at the end of a test run.
  
  def threading_setup():
      if thread:
          return thread._count(),
      else:
          return 1,
  
  def threading_cleanup(nb_threads):
      if not thread:
          return
  
      _MAX_COUNT = 10
      for count in range(_MAX_COUNT):
          n = thread._count()
          if n == nb_threads:
              break
          time.sleep(0.1)
      # XXX print a warning in case of failure?
  
  def reap_threads(func):
      """Use this function when threads are being used.  This will
      ensure that the threads are cleaned up even when the test fails.
      If threading is unavailable this function does nothing.
      """
      if not thread:
          return func
  
      @functools.wraps(func)
      def decorator(*args):
          key = threading_setup()
          try:
              return func(*args)
          finally:
              threading_cleanup(*key)
      return decorator
  
  def reap_children():
      """Use this function at the end of test_main() whenever sub-processes
      are started.  This will help ensure that no extra children (zombies)
      stick around to hog resources and create problems when looking
      for refleaks.
      """
  
      # Reap all our dead child processes so we don't leave zombies around.
      # These hog resources and might be causing some of the buildbots to die.
      if hasattr(os, 'waitpid'):
          any_process = -1
          while True:
              try:
                  # This will raise an exception on Windows.  That's ok.
                  pid, status = os.waitpid(any_process, os.WNOHANG)
                  if pid == 0:
                      break
              except:
                  break
  
  def py3k_bytes(b):
      """Emulate the py3k bytes() constructor.
  
      NOTE: This is only a best effort function.
      """
      try:
          # memoryview?
          return b.tobytes()
      except AttributeError:
          try:
              # iterable of ints?
              return b"".join(chr(x) for x in b)
          except TypeError:
              return bytes(b)
  
  def args_from_interpreter_flags():
      """Return a list of command-line arguments reproducing the current
      settings in sys.flags."""
      flag_opt_map = {
          'bytes_warning': 'b',
          'dont_write_bytecode': 'B',
          'ignore_environment': 'E',
          'no_user_site': 's',
          'no_site': 'S',
          'optimize': 'O',
          'py3k_warning': '3',
          'verbose': 'v',
      }
      args = []
      for flag, opt in flag_opt_map.items():
          v = getattr(sys.flags, flag)
          if v > 0:
              args.append('-' + opt * v)
      return args
  
  def strip_python_stderr(stderr):
      """Strip the stderr of a Python process from potential debug output
      emitted by the interpreter.
  
      This will typically be run on the result of the communicate() method
      of a subprocess.Popen object.
      """
      stderr = re.sub(br"\[\d+ refs\]\r?\n?$", b"", stderr).strip()
      return stderr
  