text: #!/usr/bin/env python
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  """Tests Google Test's throw-on-failure mode with exceptions disabled.
  
  This script invokes gtest_throw_on_failure_test_ (a program written with
  Google Test) with different environments and command line flags.
  """
  
  __author__ = 'wan@google.com (Zhanyong Wan)'
  
  import os
  import gtest_test_utils
  
  # Constants.
  
  # The command line flag for enabling/disabling the throw-on-failure mode.
  THROW_ON_FAILURE = 'gtest_throw_on_failure'
  
  # Path to the gtest_throw_on_failure_test_ program, compiled with
  # exceptions disabled.
  EXE_PATH = gtest_test_utils.GetTestExecutablePath(
      'gtest_throw_on_failure_test_')
  
  
  # Utilities.
  
  
  def SetEnvVar(env_var, value):
      """Sets an environment variable to a given value; unsets it when the
      given value is None.
      """
  
      env_var = env_var.upper()
      if value is not None:
          os.environ[env_var] = value
      elif env_var in os.environ:
          del os.environ[env_var]
  
  
  def Run(command):
      """Runs a command; returns True/False if its exit code is/isn't 0."""
  
      print 'Running "%s". . .' % ' '.join(command)
      p = gtest_test_utils.Subprocess(command)
      return p.exited and p.exit_code == 0
  
  
  # The tests.  TODO(wan@google.com): refactor the class to share common
  # logic with code in gtest_break_on_failure_unittest.py.
  class ThrowOnFailureTest(gtest_test_utils.TestCase):
      """Tests the throw-on-failure mode."""
  
      def RunAndVerify(self, env_var_value, flag_value, should_fail):
          """Runs gtest_throw_on_failure_test_ and verifies that it does
          (or does not) exit with a non-zero code.
  
          Args:
            env_var_value:    value of the GTEST_BREAK_ON_FAILURE environment
                              variable; None if the variable should be unset.
            flag_value:       value of the --gtest_break_on_failure flag;
                              None if the flag should not be present.
            should_fail:      True iff the program is expected to fail.
          """
  
          SetEnvVar(THROW_ON_FAILURE, env_var_value)
  
          if env_var_value is None:
              env_var_value_msg = ' is not set'
          else:
              env_var_value_msg = '=' + env_var_value
  
          if flag_value is None:
              flag = ''
          elif flag_value == '0':
              flag = '--%s=0' % THROW_ON_FAILURE
          else:
              flag = '--%s' % THROW_ON_FAILURE
  
          command = [EXE_PATH]
          if flag:
              command.append(flag)
  
          if should_fail:
              should_or_not = 'should'
          else:
              should_or_not = 'should not'
  
          failed = not Run(command)
  
          SetEnvVar(THROW_ON_FAILURE, None)
  
          msg = ('when %s%s, an assertion failure in "%s" %s cause a non-zero '
                 'exit code.' %
                 (THROW_ON_FAILURE, env_var_value_msg, ' '.join(command),
                  should_or_not))
          self.assert_(failed == should_fail, msg)
  
      def testDefaultBehavior(self):
          """Tests the behavior of the default mode."""
  
          self.RunAndVerify(env_var_value=None, flag_value=None, should_fail=False)
  
      def testThrowOnFailureEnvVar(self):
          """Tests using the GTEST_THROW_ON_FAILURE environment variable."""
  
          self.RunAndVerify(env_var_value='0',
                            flag_value=None,
                            should_fail=False)
          self.RunAndVerify(env_var_value='1',
                            flag_value=None,
                            should_fail=True)
  
      def testThrowOnFailureFlag(self):
          """Tests using the --gtest_throw_on_failure flag."""
  
          self.RunAndVerify(env_var_value=None,
                            flag_value='0',
                            should_fail=False)
          self.RunAndVerify(env_var_value=None,
                            flag_value='1',
                            should_fail=True)
  
      def testThrowOnFailureFlagOverridesEnvVar(self):
          """Tests that --gtest_throw_on_failure overrides GTEST_THROW_ON_FAILURE."""
  
          self.RunAndVerify(env_var_value='0',
                            flag_value='0',
                            should_fail=False)
          self.RunAndVerify(env_var_value='0',
                            flag_value='1',
                            should_fail=True)
          self.RunAndVerify(env_var_value='1',
                            flag_value='0',
                            should_fail=False)
          self.RunAndVerify(env_var_value='1',
                            flag_value='1',
                            should_fail=True)
  
  
  if __name__ == '__main__':
      gtest_test_utils.Main()
  