text: #!/usr/bin/env python
  #
  # Copyright 2006, Google Inc.
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  #
  # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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  # OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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  # LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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  # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  
  """Unit test utilities for Google C++ Testing Framework."""
  
  __author__ = 'wan@google.com (Zhanyong Wan)'
  
  import atexit
  import os
  import shutil
  import sys
  import tempfile
  import unittest
  _test_module = unittest
  
  # Suppresses the 'Import not at the top of the file' lint complaint.
  # pylint: disable-msg=C6204
  try:
    import subprocess
    _SUBPROCESS_MODULE_AVAILABLE = True
  except:
    import popen2
    _SUBPROCESS_MODULE_AVAILABLE = False
  # pylint: enable-msg=C6204
  
  GTEST_OUTPUT_VAR_NAME = 'GTEST_OUTPUT'
  
  IS_WINDOWS = os.name == 'nt'
  IS_CYGWIN = os.name == 'posix' and 'CYGWIN' in os.uname()[0]
  
  # The environment variable for specifying the path to the premature-exit file.
  PREMATURE_EXIT_FILE_ENV_VAR = 'TEST_PREMATURE_EXIT_FILE'
  
  environ = os.environ.copy()
  
  
  def SetEnvVar(env_var, value):
    """Sets/unsets an environment variable to a given value."""
  
    if value is not None:
      environ[env_var] = value
    elif env_var in environ:
      del environ[env_var]
  
  
  # Here we expose a class from a particular module, depending on the
  # environment. The comment suppresses the 'Invalid variable name' lint
  # complaint.
  TestCase = _test_module.TestCase  # pylint: disable-msg=C6409
  
  # Initially maps a flag to its default value. After
  # _ParseAndStripGTestFlags() is called, maps a flag to its actual value.
  _flag_map = {'source_dir': os.path.dirname(sys.argv[0]),
               'build_dir': os.path.dirname(sys.argv[0])}
  _gtest_flags_are_parsed = False
  
  
  def _ParseAndStripGTestFlags(argv):
    """Parses and strips Google Test flags from argv.  This is idempotent."""
  
    # Suppresses the lint complaint about a global variable since we need it
    # here to maintain module-wide state.
    global _gtest_flags_are_parsed  # pylint: disable-msg=W0603
    if _gtest_flags_are_parsed:
      return
  
    _gtest_flags_are_parsed = True
    for flag in _flag_map:
      # The environment variable overrides the default value.
      if flag.upper() in os.environ:
        _flag_map[flag] = os.environ[flag.upper()]
  
      # The command line flag overrides the environment variable.
      i = 1  # Skips the program name.
      while i < len(argv):
        prefix = '--' + flag + '='
        if argv[i].startswith(prefix):
          _flag_map[flag] = argv[i][len(prefix):]
          del argv[i]
          break
        else:
          # We don't increment i in case we just found a --gtest_* flag
          # and removed it from argv.
          i += 1
  
  
  def GetFlag(flag):
    """Returns the value of the given flag."""
  
    # In case GetFlag() is called before Main(), we always call
    # _ParseAndStripGTestFlags() here to make sure the --gtest_* flags
    # are parsed.
    _ParseAndStripGTestFlags(sys.argv)
  
    return _flag_map[flag]
  
  
  def GetSourceDir():
    """Returns the absolute path of the directory where the .py files are."""
  
    return os.path.abspath(GetFlag('source_dir'))
  
  
  def GetBuildDir():
    """Returns the absolute path of the directory where the test binaries are."""
  
    return os.path.abspath(GetFlag('build_dir'))
  
  
  _temp_dir = None
  
  def _RemoveTempDir():
    if _temp_dir:
      shutil.rmtree(_temp_dir, ignore_errors=True)
  
  atexit.register(_RemoveTempDir)
  
  
  def GetTempDir():
    """Returns a directory for temporary files."""
  
    global _temp_dir
    if not _temp_dir:
      _temp_dir = tempfile.mkdtemp()
    return _temp_dir
  
  
  def GetTestExecutablePath(executable_name, build_dir=None):
    """Returns the absolute path of the test binary given its name.
  
    The function will print a message and abort the program if the resulting file
    doesn't exist.
  
    Args:
      executable_name: name of the test binary that the test script runs.
      build_dir:       directory where to look for executables, by default
                       the result of GetBuildDir().
  
    Returns:
      The absolute path of the test binary.
    """
  
    path = os.path.abspath(os.path.join(build_dir or GetBuildDir(),
                                        executable_name))
    if (IS_WINDOWS or IS_CYGWIN) and not path.endswith('.exe'):
      path += '.exe'
  
    if not os.path.exists(path):
      message = (
          'Unable to find the test binary "%s". Please make sure to provide\n'
          'a path to the binary via the --build_dir flag or the BUILD_DIR\n'
          'environment variable.' % path)
      sys.stdout.write(message)
      sys.exit(1)
  
    return path
  
  
  def GetExitStatus(exit_code):
    """Returns the argument to exit(), or -1 if exit() wasn't called.
  
    Args:
      exit_code: the result value of os.system(command).
    """
  
    if os.name == 'nt':
      # On Windows, os.WEXITSTATUS() doesn't work and os.system() returns
      # the argument to exit() directly.
      return exit_code
    else:
      # On Unix, os.WEXITSTATUS() must be used to extract the exit status
      # from the result of os.system().
      if os.WIFEXITED(exit_code):
        return os.WEXITSTATUS(exit_code)
      else:
        return -1
  
  
  class Subprocess:
    def __init__(self, command, working_dir=None, capture_stderr=True, env=None):
      """Changes into a specified directory, if provided, and executes a command.
  
      Restores the old directory afterwards.
  
      Args:
        command:        The command to run, in the form of sys.argv.
        working_dir:    The directory to change into.
        capture_stderr: Determines whether to capture stderr in the output member
                        or to discard it.
        env:            Dictionary with environment to pass to the subprocess.
  
      Returns:
        An object that represents outcome of the executed process. It has the
        following attributes:
          terminated_by_signal   True iff the child process has been terminated
                                 by a signal.
          signal                 Sygnal that terminated the child process.
          exited                 True iff the child process exited normally.
          exit_code              The code with which the child process exited.
          output                 Child process's stdout and stderr output
                                 combined in a string.
      """
  
      # The subprocess module is the preferrable way of running programs
      # since it is available and behaves consistently on all platforms,
      # including Windows. But it is only available starting in python 2.4.
      # In earlier python versions, we revert to the popen2 module, which is
      # available in python 2.0 and later but doesn't provide required
      # functionality (Popen4) under Windows. This allows us to support Mac
      # OS X 10.4 Tiger, which has python 2.3 installed.
      if _SUBPROCESS_MODULE_AVAILABLE:
        if capture_stderr:
          stderr = subprocess.STDOUT
        else:
          stderr = subprocess.PIPE
  
        p = subprocess.Popen(command,
                             stdout=subprocess.PIPE, stderr=stderr,
                             cwd=working_dir, universal_newlines=True, env=env)
        # communicate returns a tuple with the file object for the child's
        # output.
        self.output = p.communicate()[0]
        self._return_code = p.returncode
      else:
        old_dir = os.getcwd()
  
        def _ReplaceEnvDict(dest, src):
          # Changes made by os.environ.clear are not inheritable by child
          # processes until Python 2.6. To produce inheritable changes we have
          # to delete environment items with the del statement.
          for key in dest.keys():
            del dest[key]
          dest.update(src)
  
        # When 'env' is not None, backup the environment variables and replace
        # them with the passed 'env'. When 'env' is None, we simply use the
        # current 'os.environ' for compatibility with the subprocess.Popen
        # semantics used above.
        if env is not None:
          old_environ = os.environ.copy()
          _ReplaceEnvDict(os.environ, env)
  
        try:
          if working_dir is not None:
            os.chdir(working_dir)
          if capture_stderr:
            p = popen2.Popen4(command)
          else:
            p = popen2.Popen3(command)
          p.tochild.close()
          self.output = p.fromchild.read()
          ret_code = p.wait()
        finally:
          os.chdir(old_dir)
  
          # Restore the old environment variables
          # if they were replaced.
          if env is not None:
            _ReplaceEnvDict(os.environ, old_environ)
  
        # Converts ret_code to match the semantics of
        # subprocess.Popen.returncode.
        if os.WIFSIGNALED(ret_code):
          self._return_code = -os.WTERMSIG(ret_code)
        else:  # os.WIFEXITED(ret_code) should return True here.
          self._return_code = os.WEXITSTATUS(ret_code)
  
      if self._return_code < 0:
        self.terminated_by_signal = True
        self.exited = False
        self.signal = -self._return_code
      else:
        self.terminated_by_signal = False
        self.exited = True
        self.exit_code = self._return_code
  
  
  def Main():
    """Runs the unit test."""
  
    # We must call _ParseAndStripGTestFlags() before calling
    # unittest.main().  Otherwise the latter will be confused by the
    # --gtest_* flags.
    _ParseAndStripGTestFlags(sys.argv)
    # The tested binaries should not be writing XML output files unless the
    # script explicitly instructs them to.
    # TODO(vladl@google.com): Move this into Subprocess when we implement
    # passing environment into it as a parameter.
    if GTEST_OUTPUT_VAR_NAME in os.environ:
      del os.environ[GTEST_OUTPUT_VAR_NAME]
  
    _test_module.main()
  