text: # Module doctest.
  # Released to the public domain 16-Jan-2001, by Tim Peters (tim@python.org).
  # Major enhancements and refactoring by:
  #     Jim Fulton
  #     Edward Loper
  
  # Provided as-is; use at your own risk; no warranty; no promises; enjoy!
  
  r"""Module doctest -- a framework for running examples in docstrings.
  
  In simplest use, end each module M to be tested with:
  
  def _test():
      import doctest
      doctest.testmod()
  
  if __name__ == "__main__":
      _test()
  
  Then running the module as a script will cause the examples in the
  docstrings to get executed and verified:
  
  python M.py
  
  This won't display anything unless an example fails, in which case the
  failing example(s) and the cause(s) of the failure(s) are printed to stdout
  (why not stderr? because stderr is a lame hack <0.2 wink>), and the final
  line of output is "Test failed.".
  
  Run it with the -v switch instead:
  
  python M.py -v
  
  and a detailed report of all examples tried is printed to stdout, along
  with assorted summaries at the end.
  
  You can force verbose mode by passing "verbose=True" to testmod, or prohibit
  it by passing "verbose=False".  In either of those cases, sys.argv is not
  examined by testmod.
  
  There are a variety of other ways to run doctests, including integration
  with the unittest framework, and support for running non-Python text
  files containing doctests.  There are also many ways to override parts
  of doctest's default behaviors.  See the Library Reference Manual for
  details.
  """
  
  __docformat__ = 'reStructuredText en'
  
  __all__ = [
      # 0, Option Flags
      'register_optionflag',
      'DONT_ACCEPT_TRUE_FOR_1',
      'DONT_ACCEPT_BLANKLINE',
      'NORMALIZE_WHITESPACE',
      'ELLIPSIS',
      'SKIP',
      'IGNORE_EXCEPTION_DETAIL',
      'COMPARISON_FLAGS',
      'REPORT_UDIFF',
      'REPORT_CDIFF',
      'REPORT_NDIFF',
      'REPORT_ONLY_FIRST_FAILURE',
      'REPORTING_FLAGS',
      'FAIL_FAST',
      # 1. Utility Functions
      # 2. Example & DocTest
      'Example',
      'DocTest',
      # 3. Doctest Parser
      'DocTestParser',
      # 4. Doctest Finder
      'DocTestFinder',
      # 5. Doctest Runner
      'DocTestRunner',
      'OutputChecker',
      'DocTestFailure',
      'UnexpectedException',
      'DebugRunner',
      # 6. Test Functions
      'testmod',
      'testfile',
      'run_docstring_examples',
      # 7. Unittest Support
      'DocTestSuite',
      'DocFileSuite',
      'set_unittest_reportflags',
      # 8. Debugging Support
      'script_from_examples',
      'testsource',
      'debug_src',
      'debug',
  ]
  
  import __future__
  import argparse
  import difflib
  import inspect
  import linecache
  import os
  import pdb
  import re
  import sys
  import traceback
  import unittest
  from io import StringIO
  from collections import namedtuple
  
  TestResults = namedtuple('TestResults', 'failed attempted')
  
  # There are 4 basic classes:
  #  - Example: a <source, want> pair, plus an intra-docstring line number.
  #  - DocTest: a collection of examples, parsed from a docstring, plus
  #    info about where the docstring came from (name, filename, lineno).
  #  - DocTestFinder: extracts DocTests from a given object's docstring and
  #    its contained objects' docstrings.
  #  - DocTestRunner: runs DocTest cases, and accumulates statistics.
  #
  # So the basic picture is:
  #
  #                             list of:
  # +------+                   +---------+                   +-------+
  # |object| --DocTestFinder-> | DocTest | --DocTestRunner-> |results|
  # +------+                   +---------+                   +-------+
  #                            | Example |
  #                            |   ...   |
  #                            | Example |
  #                            +---------+
  
  # Option constants.
  
  OPTIONFLAGS_BY_NAME = {}
  def register_optionflag(name):
      # Create a new flag unless `name` is already known.
      return OPTIONFLAGS_BY_NAME.setdefault(name, 1 << len(OPTIONFLAGS_BY_NAME))
  
  DONT_ACCEPT_TRUE_FOR_1 = register_optionflag('DONT_ACCEPT_TRUE_FOR_1')
  DONT_ACCEPT_BLANKLINE = register_optionflag('DONT_ACCEPT_BLANKLINE')
  NORMALIZE_WHITESPACE = register_optionflag('NORMALIZE_WHITESPACE')
  ELLIPSIS = register_optionflag('ELLIPSIS')
  SKIP = register_optionflag('SKIP')
  IGNORE_EXCEPTION_DETAIL = register_optionflag('IGNORE_EXCEPTION_DETAIL')
  
  COMPARISON_FLAGS = (DONT_ACCEPT_TRUE_FOR_1 |
                      DONT_ACCEPT_BLANKLINE |
                      NORMALIZE_WHITESPACE |
                      ELLIPSIS |
                      SKIP |
                      IGNORE_EXCEPTION_DETAIL)
  
  REPORT_UDIFF = register_optionflag('REPORT_UDIFF')
  REPORT_CDIFF = register_optionflag('REPORT_CDIFF')
  REPORT_NDIFF = register_optionflag('REPORT_NDIFF')
  REPORT_ONLY_FIRST_FAILURE = register_optionflag('REPORT_ONLY_FIRST_FAILURE')
  FAIL_FAST = register_optionflag('FAIL_FAST')
  
  REPORTING_FLAGS = (REPORT_UDIFF |
                     REPORT_CDIFF |
                     REPORT_NDIFF |
                     REPORT_ONLY_FIRST_FAILURE |
                     FAIL_FAST)
  
  # Special string markers for use in `want` strings:
  BLANKLINE_MARKER = '<BLANKLINE>'
  ELLIPSIS_MARKER = '...'
  
  ######################################################################
  ## Table of Contents
  ######################################################################
  #  1. Utility Functions
  #  2. Example & DocTest -- store test cases
  #  3. DocTest Parser -- extracts examples from strings
  #  4. DocTest Finder -- extracts test cases from objects
  #  5. DocTest Runner -- runs test cases
  #  6. Test Functions -- convenient wrappers for testing
  #  7. Unittest Support
  #  8. Debugging Support
  #  9. Example Usage
  
  ######################################################################
  ## 1. Utility Functions
  ######################################################################
  
  def _extract_future_flags(globs):
      """
      Return the compiler-flags associated with the future features that
      have been imported into the given namespace (globs).
      """
      flags = 0
      for fname in __future__.all_feature_names:
          feature = globs.get(fname, None)
          if feature is getattr(__future__, fname):
              flags |= feature.compiler_flag
      return flags
  
  def _normalize_module(module, depth=2):
      """
      Return the module specified by `module`.  In particular:
        - If `module` is a module, then return module.
        - If `module` is a string, then import and return the
          module with that name.
        - If `module` is None, then return the calling module.
          The calling module is assumed to be the module of
          the stack frame at the given depth in the call stack.
      """
      if inspect.ismodule(module):
          return module
      elif isinstance(module, str):
          return __import__(module, globals(), locals(), ["*"])
      elif module is None:
          return sys.modules[sys._getframe(depth).f_globals['__name__']]
      else:
          raise TypeError("Expected a module, string, or None")
  
  def _load_testfile(filename, package, module_relative, encoding):
      if module_relative:
          package = _normalize_module(package, 3)
          filename = _module_relative_path(package, filename)
          if getattr(package, '__loader__', None) is not None:
              if hasattr(package.__loader__, 'get_data'):
                  file_contents = package.__loader__.get_data(filename)
                  file_contents = file_contents.decode(encoding)
                  # get_data() opens files as 'rb', so one must do the equivalent
                  # conversion as universal newlines would do.
                  return file_contents.replace(os.linesep, '\n'), filename
      with open(filename, encoding=encoding) as f:
          return f.read(), filename
  
  def _indent(s, indent=4):
      """
      Add the given number of space characters to the beginning of
      every non-blank line in `s`, and return the result.
      """
      # This regexp matches the start of non-blank lines:
      return re.sub('(?m)^(?!$)', indent*' ', s)
  
  def _exception_traceback(exc_info):
      """
      Return a string containing a traceback message for the given
      exc_info tuple (as returned by sys.exc_info()).
      """
      # Get a traceback message.
      excout = StringIO()
      exc_type, exc_val, exc_tb = exc_info
      traceback.print_exception(exc_type, exc_val, exc_tb, file=excout)
      return excout.getvalue()
  
  # Override some StringIO methods.
  class _SpoofOut(StringIO):
      def getvalue(self):
          result = StringIO.getvalue(self)
          # If anything at all was written, make sure there's a trailing
          # newline.  There's no way for the expected output to indicate
          # that a trailing newline is missing.
          if result and not result.endswith("\n"):
              result += "\n"
          return result
  
      def truncate(self, size=None):
          self.seek(size)
          StringIO.truncate(self)
  
  # Worst-case linear-time ellipsis matching.
  def _ellipsis_match(want, got):
      """
      Essentially the only subtle case:
      >>> _ellipsis_match('aa...aa', 'aaa')
      False
      """
      if ELLIPSIS_MARKER not in want:
          return want == got
  
      # Find "the real" strings.
      ws = want.split(ELLIPSIS_MARKER)
      assert len(ws) >= 2
  
      # Deal with exact matches possibly needed at one or both ends.
      startpos, endpos = 0, len(got)
      w = ws[0]
      if w:   # starts with exact match
          if got.startswith(w):
              startpos = len(w)
              del ws[0]
          else:
              return False
      w = ws[-1]
      if w:   # ends with exact match
          if got.endswith(w):
              endpos -= len(w)
              del ws[-1]
          else:
              return False
  
      if startpos > endpos:
          # Exact end matches required more characters than we have, as in
          # _ellipsis_match('aa...aa', 'aaa')
          return False
  
      # For the rest, we only need to find the leftmost non-overlapping
      # match for each piece.  If there's no overall match that way alone,
      # there's no overall match period.
      for w in ws:
          # w may be '' at times, if there are consecutive ellipses, or
          # due to an ellipsis at the start or end of `want`.  That's OK.
          # Search for an empty string succeeds, and doesn't change startpos.
          startpos = got.find(w, startpos, endpos)
          if startpos < 0:
              return False
          startpos += len(w)
  
      return True
  
  def _comment_line(line):
      "Return a commented form of the given line"
      line = line.rstrip()
      if line:
          return '# '+line
      else:
          return '#'
  
  def _strip_exception_details(msg):
      # Support for IGNORE_EXCEPTION_DETAIL.
      # Get rid of everything except the exception name; in particular, drop
      # the possibly dotted module path (if any) and the exception message (if
      # any).  We assume that a colon is never part of a dotted name, or of an
      # exception name.
      # E.g., given
      #    "foo.bar.MyError: la di da"
      # return "MyError"
      # Or for "abc.def" or "abc.def:\n" return "def".
  
      start, end = 0, len(msg)
      # The exception name must appear on the first line.
      i = msg.find("\n")
      if i >= 0:
          end = i
      # retain up to the first colon (if any)
      i = msg.find(':', 0, end)
      if i >= 0:
          end = i
      # retain just the exception name
      i = msg.rfind('.', 0, end)
      if i >= 0:
          start = i+1
      return msg[start: end]
  
  class _OutputRedirectingPdb(pdb.Pdb):
      """
      A specialized version of the python debugger that redirects stdout
      to a given stream when interacting with the user.  Stdout is *not*
      redirected when traced code is executed.
      """
      def __init__(self, out):
          self.__out = out
          self.__debugger_used = False
          # do not play signal games in the pdb
          pdb.Pdb.__init__(self, stdout=out, nosigint=True)
          # still use input() to get user input
          self.use_rawinput = 1
  
      def set_trace(self, frame=None):
          self.__debugger_used = True
          if frame is None:
              frame = sys._getframe().f_back
          pdb.Pdb.set_trace(self, frame)
  
      def set_continue(self):
          # Calling set_continue unconditionally would break unit test
          # coverage reporting, as Bdb.set_continue calls sys.settrace(None).
          if self.__debugger_used:
              pdb.Pdb.set_continue(self)
  
      def trace_dispatch(self, *args):
          # Redirect stdout to the given stream.
          save_stdout = sys.stdout
          sys.stdout = self.__out
          # Call Pdb's trace dispatch method.
          try:
              return pdb.Pdb.trace_dispatch(self, *args)
          finally:
              sys.stdout = save_stdout
  
  # [XX] Normalize with respect to os.path.pardir?
  def _module_relative_path(module, test_path):
      if not inspect.ismodule(module):
          raise TypeError('Expected a module: %r' % module)
      if test_path.startswith('/'):
          raise ValueError('Module-relative files may not have absolute paths')
  
      # Normalize the path. On Windows, replace "/" with "\".
      test_path = os.path.join(*(test_path.split('/')))
  
      # Find the base directory for the path.
      if hasattr(module, '__file__'):
          # A normal module/package
          basedir = os.path.split(module.__file__)[0]
      elif module.__name__ == '__main__':
          # An interactive session.
          if len(sys.argv)>0 and sys.argv[0] != '':
              basedir = os.path.split(sys.argv[0])[0]
          else:
              basedir = os.curdir
      else:
          if hasattr(module, '__path__'):
              for directory in module.__path__:
                  fullpath = os.path.join(directory, test_path)
                  if os.path.exists(fullpath):
                      return fullpath
  
          # A module w/o __file__ (this includes builtins)
          raise ValueError("Can't resolve paths relative to the module "
                           "%r (it has no __file__)"
                           % module.__name__)
  
      # Combine the base directory and the test path.
      return os.path.join(basedir, test_path)
  
  ######################################################################
  ## 2. Example & DocTest
  ######################################################################
  ## - An "example" is a <source, want> pair, where "source" is a
  ##   fragment of source code, and "want" is the expected output for
  ##   "source."  The Example class also includes information about
  ##   where the example was extracted from.
  ##
  ## - A "doctest" is a collection of examples, typically extracted from
  ##   a string (such as an object's docstring).  The DocTest class also
  ##   includes information about where the string was extracted from.
  
  class Example:
      """
      A single doctest example, consisting of source code and expected
      output.  `Example` defines the following attributes:
  
        - source: A single Python statement, always ending with a newline.
          The constructor adds a newline if needed.
  
        - want: The expected output from running the source code (either
          from stdout, or a traceback in case of exception).  `want` ends
          with a newline unless it's empty, in which case it's an empty
          string.  The constructor adds a newline if needed.
  
        - exc_msg: The exception message generated by the example, if
          the example is expected to generate an exception; or `None` if
          it is not expected to generate an exception.  This exception
          message is compared against the return value of
          `traceback.format_exception_only()`.  `exc_msg` ends with a
          newline unless it's `None`.  The constructor adds a newline
          if needed.
  
        - lineno: The line number within the DocTest string containing
          this Example where the Example begins.  This line number is
          zero-based, with respect to the beginning of the DocTest.
  
        - indent: The example's indentation in the DocTest string.
          I.e., the number of space characters that precede the
          example's first prompt.
  
        - options: A dictionary mapping from option flags to True or
          False, which is used to override default options for this
          example.  Any option flags not contained in this dictionary
          are left at their default value (as specified by the
          DocTestRunner's optionflags).  By default, no options are set.
      """
      def __init__(self, source, want, exc_msg=None, lineno=0, indent=0,
                   options=None):
          # Normalize inputs.
          if not source.endswith('\n'):
              source += '\n'
          if want and not want.endswith('\n'):
              want += '\n'
          if exc_msg is not None and not exc_msg.endswith('\n'):
              exc_msg += '\n'
          # Store properties.
          self.source = source
          self.want = want
          self.lineno = lineno
          self.indent = indent
          if options is None: options = {}
          self.options = options
          self.exc_msg = exc_msg
  
      def __eq__(self, other):
          if type(self) is not type(other):
              return NotImplemented
  
          return self.source == other.source and \
                 self.want == other.want and \
                 self.lineno == other.lineno and \
                 self.indent == other.indent and \
                 self.options == other.options and \
                 self.exc_msg == other.exc_msg
  
      def __hash__(self):
          return hash((self.source, self.want, self.lineno, self.indent,
                       self.exc_msg))
  
  class DocTest:
      """
      A collection of doctest examples that should be run in a single
      namespace.  Each `DocTest` defines the following attributes:
  
        - examples: the list of examples.
  
        - globs: The namespace (aka globals) that the examples should
          be run in.
  
        - name: A name identifying the DocTest (typically, the name of
          the object whose docstring this DocTest was extracted from).
  
        - filename: The name of the file that this DocTest was extracted
          from, or `None` if the filename is unknown.
  
        - lineno: The line number within filename where this DocTest
          begins, or `None` if the line number is unavailable.  This
          line number is zero-based, with respect to the beginning of
          the file.
  
        - docstring: The string that the examples were extracted from,
          or `None` if the string is unavailable.
      """
      def __init__(self, examples, globs, name, filename, lineno, docstring):
          """
          Create a new DocTest containing the given examples.  The
          DocTest's globals are initialized with a copy of `globs`.
          """
          assert not isinstance(examples, str), \
                 "DocTest no longer accepts str; use DocTestParser instead"
          self.examples = examples
          self.docstring = docstring
          self.globs = globs.copy()
          self.name = name
          self.filename = filename
          self.lineno = lineno
  
      def __repr__(self):
          if len(self.examples) == 0:
              examples = 'no examples'
          elif len(self.examples) == 1:
              examples = '1 example'
          else:
              examples = '%d examples' % len(self.examples)
          return ('<%s %s from %s:%s (%s)>' %
                  (self.__class__.__name__,
                   self.name, self.filename, self.lineno, examples))
  
      def __eq__(self, other):
          if type(self) is not type(other):
              return NotImplemented
  
          return self.examples == other.examples and \
                 self.docstring == other.docstring and \
                 self.globs == other.globs and \
                 self.name == other.name and \
                 self.filename == other.filename and \
                 self.lineno == other.lineno
  
      def __hash__(self):
          return hash((self.docstring, self.name, self.filename, self.lineno))
  
      # This lets us sort tests by name:
      def __lt__(self, other):
          if not isinstance(other, DocTest):
              return NotImplemented
          return ((self.name, self.filename, self.lineno, id(self))
                  <
                  (other.name, other.filename, other.lineno, id(other)))
  
  ######################################################################
  ## 3. DocTestParser
  ######################################################################
  
  class DocTestParser:
      """
      A class used to parse strings containing doctest examples.
      """
      # This regular expression is used to find doctest examples in a
      # string.  It defines three groups: `source` is the source code
      # (including leading indentation and prompts); `indent` is the
      # indentation of the first (PS1) line of the source code; and
      # `want` is the expected output (including leading indentation).
      _EXAMPLE_RE = re.compile(r'''
          # Source consists of a PS1 line followed by zero or more PS2 lines.
          (?P<source>
              (?:^(?P<indent> [ ]*) >>>    .*)    # PS1 line
              (?:\n           [ ]*  \.\.\. .*)*)  # PS2 lines
          \n?
          # Want consists of any non-blank lines that do not start with PS1.
          (?P<want> (?:(?![ ]*$)    # Not a blank line
                       (?![ ]*>>>)  # Not a line starting with PS1
                       .+$\n?       # But any other line
                    )*)
          ''', re.MULTILINE | re.VERBOSE)
  
      # A regular expression for handling `want` strings that contain
      # expected exceptions.  It divides `want` into three pieces:
      #    - the traceback header line (`hdr`)
      #    - the traceback stack (`stack`)
      #    - the exception message (`msg`), as generated by
      #      traceback.format_exception_only()
      # `msg` may have multiple lines.  We assume/require that the
      # exception message is the first non-indented line starting with a word
      # character following the traceback header line.
      _EXCEPTION_RE = re.compile(r"""
          # Grab the traceback header.  Different versions of Python have
          # said different things on the first traceback line.
          ^(?P<hdr> Traceback\ \(
              (?: most\ recent\ call\ last
              |   innermost\ last
              ) \) :
          )
          \s* $                # toss trailing whitespace on the header.
          (?P<stack> .*?)      # don't blink: absorb stuff until...
          ^ (?P<msg> \w+ .*)   #     a line *starts* with alphanum.
          """, re.VERBOSE | re.MULTILINE | re.DOTALL)
  
      # A callable returning a true value iff its argument is a blank line
      # or contains a single comment.
      _IS_BLANK_OR_COMMENT = re.compile(r'^[ ]*(#.*)?$').match
  
      def parse(self, string, name='<string>'):
          """
          Divide the given string into examples and intervening text,
          and return them as a list of alternating Examples and strings.
          Line numbers for the Examples are 0-based.  The optional
          argument `name` is a name identifying this string, and is only
          used for error messages.
          """
          string = string.expandtabs()
          # If all lines begin with the same indentation, then strip it.
          min_indent = self._min_indent(string)
          if min_indent > 0:
              string = '\n'.join([l[min_indent:] for l in string.split('\n')])
  
          output = []
          charno, lineno = 0, 0
          # Find all doctest examples in the string:
          for m in self._EXAMPLE_RE.finditer(string):
              # Add the pre-example text to `output`.
              output.append(string[charno:m.start()])
              # Update lineno (lines before this example)
              lineno += string.count('\n', charno, m.start())
              # Extract info from the regexp match.
              (source, options, want, exc_msg) = \
                       self._parse_example(m, name, lineno)
              # Create an Example, and add it to the list.
              if not self._IS_BLANK_OR_COMMENT(source):
                  output.append( Example(source, want, exc_msg,
                                      lineno=lineno,
                                      indent=min_indent+len(m.group('indent')),
                                      options=options) )
              # Update lineno (lines inside this example)
              lineno += string.count('\n', m.start(), m.end())
              # Update charno.
              charno = m.end()
          # Add any remaining post-example text to `output`.
          output.append(string[charno:])
          return output
  
      def get_doctest(self, string, globs, name, filename, lineno):
          """
          Extract all doctest examples from the given string, and
          collect them into a `DocTest` object.
  
          `globs`, `name`, `filename`, and `lineno` are attributes for
          the new `DocTest` object.  See the documentation for `DocTest`
          for more information.
          """
          return DocTest(self.get_examples(string, name), globs,
                         name, filename, lineno, string)
  
      def get_examples(self, string, name='<string>'):
          """
          Extract all doctest examples from the given string, and return
          them as a list of `Example` objects.  Line numbers are
          0-based, because it's most common in doctests that nothing
          interesting appears on the same line as opening triple-quote,
          and so the first interesting line is called \"line 1\" then.
  
          The optional argument `name` is a name identifying this
          string, and is only used for error messages.
          """
          return [x for x in self.parse(string, name)
                  if isinstance(x, Example)]
  
      def _parse_example(self, m, name, lineno):
          """
          Given a regular expression match from `_EXAMPLE_RE` (`m`),
          return a pair `(source, want)`, where `source` is the matched
          example's source code (with prompts and indentation stripped);
          and `want` is the example's expected output (with indentation
          stripped).
  
          `name` is the string's name, and `lineno` is the line number
          where the example starts; both are used for error messages.
          """
          # Get the example's indentation level.
          indent = len(m.group('indent'))
  
          # Divide source into lines; check that they're properly
          # indented; and then strip their indentation & prompts.
          source_lines = m.group('source').split('\n')
          self._check_prompt_blank(source_lines, indent, name, lineno)
          self._check_prefix(source_lines[1:], ' '*indent + '.', name, lineno)
          source = '\n'.join([sl[indent+4:] for sl in source_lines])
  
          # Divide want into lines; check that it's properly indented; and
          # then strip the indentation.  Spaces before the last newline should
          # be preserved, so plain rstrip() isn't good enough.
          want = m.group('want')
          want_lines = want.split('\n')
          if len(want_lines) > 1 and re.match(r' *$', want_lines[-1]):
              del want_lines[-1]  # forget final newline & spaces after it
          self._check_prefix(want_lines, ' '*indent, name,
                             lineno + len(source_lines))
          want = '\n'.join([wl[indent:] for wl in want_lines])
  
          # If `want` contains a traceback message, then extract it.
          m = self._EXCEPTION_RE.match(want)
          if m:
              exc_msg = m.group('msg')
          else:
              exc_msg = None
  
          # Extract options from the source.
          options = self._find_options(source, name, lineno)
  
          return source, options, want, exc_msg
  
      # This regular expression looks for option directives in the
      # source code of an example.  Option directives are comments
      # starting with "doctest:".  Warning: this may give false
      # positives for string-literals that contain the string
      # "#doctest:".  Eliminating these false positives would require
      # actually parsing the string; but we limit them by ignoring any
      # line containing "#doctest:" that is *followed* by a quote mark.
      _OPTION_DIRECTIVE_RE = re.compile(r'#\s*doctest:\s*([^\n\'"]*)$',
                                        re.MULTILINE)
  
      def _find_options(self, source, name, lineno):
          """
          Return a dictionary containing option overrides extracted from
          option directives in the given source string.
  
          `name` is the string's name, and `lineno` is the line number
          where the example starts; both are used for error messages.
          """
          options = {}
          # (note: with the current regexp, this will match at most once:)
          for m in self._OPTION_DIRECTIVE_RE.finditer(source):
              option_strings = m.group(1).replace(',', ' ').split()
              for option in option_strings:
                  if (option[0] not in '+-' or
                      option[1:] not in OPTIONFLAGS_BY_NAME):
                      raise ValueError('line %r of the doctest for %s '
                                       'has an invalid option: %r' %
                                       (lineno+1, name, option))
                  flag = OPTIONFLAGS_BY_NAME[option[1:]]
                  options[flag] = (option[0] == '+')
          if options and self._IS_BLANK_OR_COMMENT(source):
              raise ValueError('line %r of the doctest for %s has an option '
                               'directive on a line with no example: %r' %
                               (lineno, name, source))
          return options
  
      # This regular expression finds the indentation of every non-blank
      # line in a string.
      _INDENT_RE = re.compile('^([ ]*)(?=\S)', re.MULTILINE)
  
      def _min_indent(self, s):
          "Return the minimum indentation of any non-blank line in `s`"
          indents = [len(indent) for indent in self._INDENT_RE.findall(s)]
          if len(indents) > 0:
              return min(indents)
          else:
              return 0
  
      def _check_prompt_blank(self, lines, indent, name, lineno):
          """
          Given the lines of a source string (including prompts and
          leading indentation), check to make sure that every prompt is
          followed by a space character.  If any line is not followed by
          a space character, then raise ValueError.
          """
          for i, line in enumerate(lines):
              if len(line) >= indent+4 and line[indent+3] != ' ':
                  raise ValueError('line %r of the docstring for %s '
                                   'lacks blank after %s: %r' %
                                   (lineno+i+1, name,
                                    line[indent:indent+3], line))
  
      def _check_prefix(self, lines, prefix, name, lineno):
          """
          Check that every line in the given list starts with the given
          prefix; if any line does not, then raise a ValueError.
          """
          for i, line in enumerate(lines):
              if line and not line.startswith(prefix):
                  raise ValueError('line %r of the docstring for %s has '
                                   'inconsistent leading whitespace: %r' %
                                   (lineno+i+1, name, line))
  
  
  ######################################################################
  ## 4. DocTest Finder
  ######################################################################
  
  class DocTestFinder:
      """
      A class used to extract the DocTests that are relevant to a given
      object, from its docstring and the docstrings of its contained
      objects.  Doctests can currently be extracted from the following
      object types: modules, functions, classes, methods, staticmethods,
      classmethods, and properties.
      """
  
      def __init__(self, verbose=False, parser=DocTestParser(),
                   recurse=True, exclude_empty=True):
          """
          Create a new doctest finder.
  
          The optional argument `parser` specifies a class or
          function that should be used to create new DocTest objects (or
          objects that implement the same interface as DocTest).  The
          signature for this factory function should match the signature
          of the DocTest constructor.
  
          If the optional argument `recurse` is false, then `find` will
          only examine the given object, and not any contained objects.
  
          If the optional argument `exclude_empty` is false, then `find`
          will include tests for objects with empty docstrings.
          """
          self._parser = parser
          self._verbose = verbose
          self._recurse = recurse
          self._exclude_empty = exclude_empty
  
      def find(self, obj, name=None, module=None, globs=None, extraglobs=None):
          """
          Return a list of the DocTests that are defined by the given
          object's docstring, or by any of its contained objects'
          docstrings.
  
          The optional parameter `module` is the module that contains
          the given object.  If the module is not specified or is None, then
          the test finder will attempt to automatically determine the
          correct module.  The object's module is used:
  
              - As a default namespace, if `globs` is not specified.
              - To prevent the DocTestFinder from extracting DocTests
                from objects that are imported from other modules.
              - To find the name of the file containing the object.
              - To help find the line number of the object within its
                file.
  
          Contained objects whose module does not match `module` are ignored.
  
          If `module` is False, no attempt to find the module will be made.
          This is obscure, of use mostly in tests:  if `module` is False, or
          is None but cannot be found automatically, then all objects are
          considered to belong to the (non-existent) module, so all contained
          objects will (recursively) be searched for doctests.
  
          The globals for each DocTest is formed by combining `globs`
          and `extraglobs` (bindings in `extraglobs` override bindings
          in `globs`).  A new copy of the globals dictionary is created
          for each DocTest.  If `globs` is not specified, then it
          defaults to the module's `__dict__`, if specified, or {}
          otherwise.  If `extraglobs` is not specified, then it defaults
          to {}.
  
          """
          # If name was not specified, then extract it from the object.
          if name is None:
              name = getattr(obj, '__name__', None)
              if name is None:
                  raise ValueError("DocTestFinder.find: name must be given "
                          "when obj.__name__ doesn't exist: %r" %
                                   (type(obj),))
  
          # Find the module that contains the given object (if obj is
          # a module, then module=obj.).  Note: this may fail, in which
          # case module will be None.
          if module is False:
              module = None
          elif module is None:
              module = inspect.getmodule(obj)
  
          # Read the module's source code.  This is used by
          # DocTestFinder._find_lineno to find the line number for a
          # given object's docstring.
          try:
              file = inspect.getsourcefile(obj)
          except TypeError:
              source_lines = None
          else:
              if not file:
                  # Check to see if it's one of our special internal "files"
                  # (see __patched_linecache_getlines).
                  file = inspect.getfile(obj)
                  if not file[0]+file[-2:] == '<]>': file = None
              if file is None:
                  source_lines = None
              else:
                  if module is not None:
                      # Supply the module globals in case the module was
                      # originally loaded via a PEP 302 loader and
                      # file is not a valid filesystem path
                      source_lines = linecache.getlines(file, module.__dict__)
                  else:
                      # No access to a loader, so assume it's a normal
                      # filesystem path
                      source_lines = linecache.getlines(file)
                  if not source_lines:
                      source_lines = None
  
          # Initialize globals, and merge in extraglobs.
          if globs is None:
              if module is None:
                  globs = {}
              else:
                  globs = module.__dict__.copy()
          else:
              globs = globs.copy()
          if extraglobs is not None:
              globs.update(extraglobs)
          if '__name__' not in globs:
              globs['__name__'] = '__main__'  # provide a default module name
  
          # Recursively explore `obj`, extracting DocTests.
          tests = []
          self._find(tests, obj, name, module, source_lines, globs, {})
          # Sort the tests by alpha order of names, for consistency in
          # verbose-mode output.  This was a feature of doctest in Pythons
          # <= 2.3 that got lost by accident in 2.4.  It was repaired in
          # 2.4.4 and 2.5.
          tests.sort()
          return tests
  
      def _from_module(self, module, object):
          """
          Return true if the given object is defined in the given
          module.
          """
          if module is None:
              return True
          elif inspect.getmodule(object) is not None:
              return module is inspect.getmodule(object)
          elif inspect.isfunction(object):
              return module.__dict__ is object.__globals__
          elif inspect.ismethoddescriptor(object):
              if hasattr(object, '__objclass__'):
                  obj_mod = object.__objclass__.__module__
              elif hasattr(object, '__module__'):
                  obj_mod = object.__module__
              else:
                  return True # [XX] no easy way to tell otherwise
              return module.__name__ == obj_mod
          elif inspect.isclass(object):
              return module.__name__ == object.__module__
          elif hasattr(object, '__module__'):
              return module.__name__ == object.__module__
          elif isinstance(object, property):
              return True # [XX] no way not be sure.
          else:
              raise ValueError("object must be a class or function")
  
      def _find(self, tests, obj, name, module, source_lines, globs, seen):
          """
          Find tests for the given object and any contained objects, and
          add them to `tests`.
          """
          if self._verbose:
              print('Finding tests in %s' % name)
  
          # If we've already processed this object, then ignore it.
          if id(obj) in seen:
              return
          seen[id(obj)] = 1
  
          # Find a test for this object, and add it to the list of tests.
          test = self._get_test(obj, name, module, globs, source_lines)
          if test is not None:
              tests.append(test)
  
          # Look for tests in a module's contained objects.
          if inspect.ismodule(obj) and self._recurse:
              for valname, val in obj.__dict__.items():
                  valname = '%s.%s' % (name, valname)
                  # Recurse to functions & classes.
                  if ((inspect.isroutine(inspect.unwrap(val))
                       or inspect.isclass(val)) and
                      self._from_module(module, val)):
                      self._find(tests, val, valname, module, source_lines,
                                 globs, seen)
  
          # Look for tests in a module's __test__ dictionary.
          if inspect.ismodule(obj) and self._recurse:
              for valname, val in getattr(obj, '__test__', {}).items():
                  if not isinstance(valname, str):
                      raise ValueError("DocTestFinder.find: __test__ keys "
                                       "must be strings: %r" %
                                       (type(valname),))
                  if not (inspect.isroutine(val) or inspect.isclass(val) or
                          inspect.ismodule(val) or isinstance(val, str)):
                      raise ValueError("DocTestFinder.find: __test__ values "
                                       "must be strings, functions, methods, "
                                       "classes, or modules: %r" %
                                       (type(val),))
                  valname = '%s.__test__.%s' % (name, valname)
                  self._find(tests, val, valname, module, source_lines,
                             globs, seen)
  
          # Look for tests in a class's contained objects.
          if inspect.isclass(obj) and self._recurse:
              for valname, val in obj.__dict__.items():
                  # Special handling for staticmethod/classmethod.
                  if isinstance(val, staticmethod):
                      val = getattr(obj, valname)
                  if isinstance(val, classmethod):
                      val = getattr(obj, valname).__func__
  
                  # Recurse to methods, properties, and nested classes.
                  if ((inspect.isroutine(val) or inspect.isclass(val) or
                        isinstance(val, property)) and
                        self._from_module(module, val)):
                      valname = '%s.%s' % (name, valname)
                      self._find(tests, val, valname, module, source_lines,
                                 globs, seen)
  
      def _get_test(self, obj, name, module, globs, source_lines):
          """
          Return a DocTest for the given object, if it defines a docstring;
          otherwise, return None.
          """
          # Extract the object's docstring.  If it doesn't have one,
          # then return None (no test for this object).
          if isinstance(obj, str):
              docstring = obj
          else:
              try:
                  if obj.__doc__ is None:
                      docstring = ''
                  else:
                      docstring = obj.__doc__
                      if not isinstance(docstring, str):
                          docstring = str(docstring)
              except (TypeError, AttributeError):
                  docstring = ''
  
          # Find the docstring's location in the file.
          lineno = self._find_lineno(obj, source_lines)
  
          # Don't bother if the docstring is empty.
          if self._exclude_empty and not docstring:
              return None
  
          # Return a DocTest for this object.
          if module is None:
              filename = None
          else:
              filename = getattr(module, '__file__', module.__name__)
              if filename[-4:] == ".pyc":
                  filename = filename[:-1]
          return self._parser.get_doctest(docstring, globs, name,
                                          filename, lineno)
  
      def _find_lineno(self, obj, source_lines):
          """
          Return a line number of the given object's docstring.  Note:
          this method assumes that the object has a docstring.
          """
          lineno = None
  
          # Find the line number for modules.
          if inspect.ismodule(obj):
              lineno = 0
  
          # Find the line number for classes.
          # Note: this could be fooled if a class is defined multiple
          # times in a single file.
          if inspect.isclass(obj):
              if source_lines is None:
                  return None
              pat = re.compile(r'^\s*class\s*%s\b' %
                               getattr(obj, '__name__', '-'))
              for i, line in enumerate(source_lines):
                  if pat.match(line):
                      lineno = i
                      break
  
          # Find the line number for functions & methods.
          if inspect.ismethod(obj): obj = obj.__func__
          if inspect.isfunction(obj): obj = obj.__code__
          if inspect.istraceback(obj): obj = obj.tb_frame
          if inspect.isframe(obj): obj = obj.f_code
          if inspect.iscode(obj):
              lineno = getattr(obj, 'co_firstlineno', None)-1
  
          # Find the line number where the docstring starts.  Assume
          # that it's the first line that begins with a quote mark.
          # Note: this could be fooled by a multiline function
          # signature, where a continuation line begins with a quote
          # mark.
          if lineno is not None:
              if source_lines is None:
                  return lineno+1
              pat = re.compile('(^|.*:)\s*\w*("|\')')
              for lineno in range(lineno, len(source_lines)):
                  if pat.match(source_lines[lineno]):
                      return lineno
  
          # We couldn't find the line number.
          return None
  
  ######################################################################
  ## 5. DocTest Runner
  ######################################################################
  
  class DocTestRunner:
      """
      A class used to run DocTest test cases, and accumulate statistics.
      The `run` method is used to process a single DocTest case.  It
      returns a tuple `(f, t)`, where `t` is the number of test cases
      tried, and `f` is the number of test cases that failed.
  
          >>> tests = DocTestFinder().find(_TestClass)
          >>> runner = DocTestRunner(verbose=False)
          >>> tests.sort(key = lambda test: test.name)
          >>> for test in tests:
          ...     print(test.name, '->', runner.run(test))
          _TestClass -> TestResults(failed=0, attempted=2)
          _TestClass.__init__ -> TestResults(failed=0, attempted=2)
          _TestClass.get -> TestResults(failed=0, attempted=2)
          _TestClass.square -> TestResults(failed=0, attempted=1)
  
      The `summarize` method prints a summary of all the test cases that
      have been run by the runner, and returns an aggregated `(f, t)`
      tuple:
  
          >>> runner.summarize(verbose=1)
          4 items passed all tests:
             2 tests in _TestClass
             2 tests in _TestClass.__init__
             2 tests in _TestClass.get
             1 tests in _TestClass.square
          7 tests in 4 items.
          7 passed and 0 failed.
          Test passed.
          TestResults(failed=0, attempted=7)
  
      The aggregated number of tried examples and failed examples is
      also available via the `tries` and `failures` attributes:
  
          >>> runner.tries
          7
          >>> runner.failures
          0
  
      The comparison between expected outputs and actual outputs is done
      by an `OutputChecker`.  This comparison may be customized with a
      number of option flags; see the documentation for `testmod` for
      more information.  If the option flags are insufficient, then the
      comparison may also be customized by passing a subclass of
      `OutputChecker` to the constructor.
  
      The test runner's display output can be controlled in two ways.
      First, an output function (`out) can be passed to
      `TestRunner.run`; this function will be called with strings that
      should be displayed.  It defaults to `sys.stdout.write`.  If
      capturing the output is not sufficient, then the display output
      can be also customized by subclassing DocTestRunner, and
      overriding the methods `report_start`, `report_success`,
      `report_unexpected_exception`, and `report_failure`.
      """
      # This divider string is used to separate failure messages, and to
      # separate sections of the summary.
      DIVIDER = "*" * 70
  
      def __init__(self, checker=None, verbose=None, optionflags=0):
          """
          Create a new test runner.
  
          Optional keyword arg `checker` is the `OutputChecker` that
          should be used to compare the expected outputs and actual
          outputs of doctest examples.
  
          Optional keyword arg 'verbose' prints lots of stuff if true,
          only failures if false; by default, it's true iff '-v' is in
          sys.argv.
  
          Optional argument `optionflags` can be used to control how the
          test runner compares expected output to actual output, and how
          it displays failures.  See the documentation for `testmod` for
          more information.
          """
          self._checker = checker or OutputChecker()
          if verbose is None:
              verbose = '-v' in sys.argv
          self._verbose = verbose
          self.optionflags = optionflags
          self.original_optionflags = optionflags
  
          # Keep track of the examples we've run.
          self.tries = 0
          self.failures = 0
          self._name2ft = {}
  
          # Create a fake output target for capturing doctest output.
          self._fakeout = _SpoofOut()
  
      #/////////////////////////////////////////////////////////////////
      # Reporting methods
      #/////////////////////////////////////////////////////////////////
  
      def report_start(self, out, test, example):
          """
          Report that the test runner is about to process the given
          example.  (Only displays a message if verbose=True)
          """
          if self._verbose:
              if example.want:
                  out('Trying:\n' + _indent(example.source) +
                      'Expecting:\n' + _indent(example.want))
              else:
                  out('Trying:\n' + _indent(example.source) +
                      'Expecting nothing\n')
  
      def report_success(self, out, test, example, got):
          """
          Report that the given example ran successfully.  (Only
          displays a message if verbose=True)
          """
          if self._verbose:
              out("ok\n")
  
      def report_failure(self, out, test, example, got):
          """
          Report that the given example failed.
          """
          out(self._failure_header(test, example) +
              self._checker.output_difference(example, got, self.optionflags))
  
      def report_unexpected_exception(self, out, test, example, exc_info):
          """
          Report that the given example raised an unexpected exception.
          """
          out(self._failure_header(test, example) +
              'Exception raised:\n' + _indent(_exception_traceback(exc_info)))
  
      def _failure_header(self, test, example):
          out = [self.DIVIDER]
          if test.filename:
              if test.lineno is not None and example.lineno is not None:
                  lineno = test.lineno + example.lineno + 1
              else:
                  lineno = '?'
              out.append('File "%s", line %s, in %s' %
                         (test.filename, lineno, test.name))
          else:
              out.append('Line %s, in %s' % (example.lineno+1, test.name))
          out.append('Failed example:')
          source = example.source
          out.append(_indent(source))
          return '\n'.join(out)
  
      #/////////////////////////////////////////////////////////////////
      # DocTest Running
      #/////////////////////////////////////////////////////////////////
  
      def __run(self, test, compileflags, out):
          """
          Run the examples in `test`.  Write the outcome of each example
          with one of the `DocTestRunner.report_*` methods, using the
          writer function `out`.  `compileflags` is the set of compiler
          flags that should be used to execute examples.  Return a tuple
          `(f, t)`, where `t` is the number of examples tried, and `f`
          is the number of examples that failed.  The examples are run
          in the namespace `test.globs`.
          """
          # Keep track of the number of failures and tries.
          failures = tries = 0
  
          # Save the option flags (since option directives can be used
          # to modify them).
          original_optionflags = self.optionflags
  
          SUCCESS, FAILURE, BOOM = range(3) # `outcome` state
  
          check = self._checker.check_output
  
          # Process each example.
          for examplenum, example in enumerate(test.examples):
  
              # If REPORT_ONLY_FIRST_FAILURE is set, then suppress
              # reporting after the first failure.
              quiet = (self.optionflags & REPORT_ONLY_FIRST_FAILURE and
                       failures > 0)
  
              # Merge in the example's options.
              self.optionflags = original_optionflags
              if example.options:
                  for (optionflag, val) in example.options.items():
                      if val:
                          self.optionflags |= optionflag
                      else:
                          self.optionflags &= ~optionflag
  
              # If 'SKIP' is set, then skip this example.
              if self.optionflags & SKIP:
                  continue
  
              # Record that we started this example.
              tries += 1
              if not quiet:
                  self.report_start(out, test, example)
  
              # Use a special filename for compile(), so we can retrieve
              # the source code during interactive debugging (see
              # __patched_linecache_getlines).
              filename = '<doctest %s[%d]>' % (test.name, examplenum)
  
              # Run the example in the given context (globs), and record
              # any exception that gets raised.  (But don't intercept
              # keyboard interrupts.)
              try:
                  # Don't blink!  This is where the user's code gets run.
                  exec(compile(example.source, filename, "single",
                               compileflags, 1), test.globs)
                  self.debugger.set_continue() # ==== Example Finished ====
                  exception = None
              except KeyboardInterrupt:
                  raise
              except:
                  exception = sys.exc_info()
                  self.debugger.set_continue() # ==== Example Finished ====
  
              got = self._fakeout.getvalue()  # the actual output
              self._fakeout.truncate(0)
              outcome = FAILURE   # guilty until proved innocent or insane
  
              # If the example executed without raising any exceptions,
              # verify its output.
              if exception is None:
                  if check(example.want, got, self.optionflags):
                      outcome = SUCCESS
  
              # The example raised an exception:  check if it was expected.
              else:
                  exc_msg = traceback.format_exception_only(*exception[:2])[-1]
                  if not quiet:
                      got += _exception_traceback(exception)
  
                  # If `example.exc_msg` is None, then we weren't expecting
                  # an exception.
                  if example.exc_msg is None:
                      outcome = BOOM
  
                  # We expected an exception:  see whether it matches.
                  elif check(example.exc_msg, exc_msg, self.optionflags):
                      outcome = SUCCESS
  
                  # Another chance if they didn't care about the detail.
                  elif self.optionflags & IGNORE_EXCEPTION_DETAIL:
                      if check(_strip_exception_details(example.exc_msg),
                               _strip_exception_details(exc_msg),
                               self.optionflags):
                          outcome = SUCCESS
  
              # Report the outcome.
              if outcome is SUCCESS:
                  if not quiet:
                      self.report_success(out, test, example, got)
              elif outcome is FAILURE:
                  if not quiet:
                      self.report_failure(out, test, example, got)
                  failures += 1
              elif outcome is BOOM:
                  if not quiet:
                      self.report_unexpected_exception(out, test, example,
                                                       exception)
                  failures += 1
              else:
                  assert False, ("unknown outcome", outcome)
  
              if failures and self.optionflags & FAIL_FAST:
                  break
  
          # Restore the option flags (in case they were modified)
          self.optionflags = original_optionflags
  
          # Record and return the number of failures and tries.
          self.__record_outcome(test, failures, tries)
          return TestResults(failures, tries)
  
      def __record_outcome(self, test, f, t):
          """
          Record the fact that the given DocTest (`test`) generated `f`
          failures out of `t` tried examples.
          """
          f2, t2 = self._name2ft.get(test.name, (0,0))
          self._name2ft[test.name] = (f+f2, t+t2)
          self.failures += f
          self.tries += t
  
      __LINECACHE_FILENAME_RE = re.compile(r'<doctest '
                                           r'(?P<name>.+)'
                                           r'\[(?P<examplenum>\d+)\]>$')
      def __patched_linecache_getlines(self, filename, module_globals=None):
          m = self.__LINECACHE_FILENAME_RE.match(filename)
          if m and m.group('name') == self.test.name:
              example = self.test.examples[int(m.group('examplenum'))]
              return example.source.splitlines(keepends=True)
          else:
              return self.save_linecache_getlines(filename, module_globals)
  
      def run(self, test, compileflags=None, out=None, clear_globs=True):
          """
          Run the examples in `test`, and display the results using the
          writer function `out`.
  
          The examples are run in the namespace `test.globs`.  If
          `clear_globs` is true (the default), then this namespace will
          be cleared after the test runs, to help with garbage
          collection.  If you would like to examine the namespace after
          the test completes, then use `clear_globs=False`.
  
          `compileflags` gives the set of flags that should be used by
          the Python compiler when running the examples.  If not
          specified, then it will default to the set of future-import
          flags that apply to `globs`.
  
          The output of each example is checked using
          `DocTestRunner.check_output`, and the results are formatted by
          the `DocTestRunner.report_*` methods.
          """
          self.test = test
  
          if compileflags is None:
              compileflags = _extract_future_flags(test.globs)
  
          save_stdout = sys.stdout
          if out is None:
              encoding = save_stdout.encoding
              if encoding is None or encoding.lower() == 'utf-8':
                  out = save_stdout.write
              else:
                  # Use backslashreplace error handling on write
                  def out(s):
                      s = str(s.encode(encoding, 'backslashreplace'), encoding)
                      save_stdout.write(s)
          sys.stdout = self._fakeout
  
          # Patch pdb.set_trace to restore sys.stdout during interactive
          # debugging (so it's not still redirected to self._fakeout).
          # Note that the interactive output will go to *our*
          # save_stdout, even if that's not the real sys.stdout; this
          # allows us to write test cases for the set_trace behavior.
          save_trace = sys.gettrace()
          save_set_trace = pdb.set_trace
          self.debugger = _OutputRedirectingPdb(save_stdout)
          self.debugger.reset()
          pdb.set_trace = self.debugger.set_trace
  
          # Patch linecache.getlines, so we can see the example's source
          # when we're inside the debugger.
          self.save_linecache_getlines = linecache.getlines
          linecache.getlines = self.__patched_linecache_getlines
  
          # Make sure sys.displayhook just prints the value to stdout
          save_displayhook = sys.displayhook
          sys.displayhook = sys.__displayhook__
  
          try:
              return self.__run(test, compileflags, out)
          finally:
              sys.stdout = save_stdout
              pdb.set_trace = save_set_trace
              sys.settrace(save_trace)
              linecache.getlines = self.save_linecache_getlines
              sys.displayhook = save_displayhook
              if clear_globs:
                  test.globs.clear()
                  import builtins
                  builtins._ = None
  
      #/////////////////////////////////////////////////////////////////
      # Summarization
      #/////////////////////////////////////////////////////////////////
      def summarize(self, verbose=None):
          """
          Print a summary of all the test cases that have been run by
          this DocTestRunner, and return a tuple `(f, t)`, where `f` is
          the total number of failed examples, and `t` is the total
          number of tried examples.
  
          The optional `verbose` argument controls how detailed the
          summary is.  If the verbosity is not specified, then the
          DocTestRunner's verbosity is used.
          """
          if verbose is None:
              verbose = self._verbose
          notests = []
          passed = []
          failed = []
          totalt = totalf = 0
          for x in self._name2ft.items():
              name, (f, t) = x
              assert f <= t
              totalt += t
              totalf += f
              if t == 0:
                  notests.append(name)
              elif f == 0:
                  passed.append( (name, t) )
              else:
                  failed.append(x)
          if verbose:
              if notests:
                  print(len(notests), "items had no tests:")
                  notests.sort()
                  for thing in notests:
                      print("   ", thing)
              if passed:
                  print(len(passed), "items passed all tests:")
                  passed.sort()
                  for thing, count in passed:
                      print(" %3d tests in %s" % (count, thing))
          if failed:
              print(self.DIVIDER)
              print(len(failed), "items had failures:")
              failed.sort()
              for thing, (f, t) in failed:
                  print(" %3d of %3d in %s" % (f, t, thing))
          if verbose:
              print(totalt, "tests in", len(self._name2ft), "items.")
              print(totalt - totalf, "passed and", totalf, "failed.")
          if totalf:
              print("***Test Failed***", totalf, "failures.")
          elif verbose:
              print("Test passed.")
          return TestResults(totalf, totalt)
  
      #/////////////////////////////////////////////////////////////////
      # Backward compatibility cruft to maintain doctest.master.
      #/////////////////////////////////////////////////////////////////
      def merge(self, other):
          d = self._name2ft
          for name, (f, t) in other._name2ft.items():
              if name in d:
                  # Don't print here by default, since doing
                  #     so breaks some of the buildbots
                  #print("*** DocTestRunner.merge: '" + name + "' in both" \
                  #    " testers; summing outcomes.")
                  f2, t2 = d[name]
                  f = f + f2
                  t = t + t2
              d[name] = f, t
  
  class OutputChecker:
      """
      A class used to check the whether the actual output from a doctest
      example matches the expected output.  `OutputChecker` defines two
      methods: `check_output`, which compares a given pair of outputs,
      and returns true if they match; and `output_difference`, which
      returns a string describing the differences between two outputs.
      """
      def _toAscii(self, s):
          """
          Convert string to hex-escaped ASCII string.
          """
          return str(s.encode('ASCII', 'backslashreplace'), "ASCII")
  
      def check_output(self, want, got, optionflags):
          """
          Return True iff the actual output from an example (`got`)
          matches the expected output (`want`).  These strings are
          always considered to match if they are identical; but
          depending on what option flags the test runner is using,
          several non-exact match types are also possible.  See the
          documentation for `TestRunner` for more information about
          option flags.
          """
  
          # If `want` contains hex-escaped character such as "\u1234",
          # then `want` is a string of six characters(e.g. [\,u,1,2,3,4]).
          # On the other hand, `got` could be another sequence of
          # characters such as [\u1234], so `want` and `got` should
          # be folded to hex-escaped ASCII string to compare.
          got = self._toAscii(got)
          want = self._toAscii(want)
  
          # Handle the common case first, for efficiency:
          # if they're string-identical, always return true.
          if got == want:
              return True
  
          # The values True and False replaced 1 and 0 as the return
          # value for boolean comparisons in Python 2.3.
          if not (optionflags & DONT_ACCEPT_TRUE_FOR_1):
              if (got,want) == ("True\n", "1\n"):
                  return True
              if (got,want) == ("False\n", "0\n"):
                  return True
  
          # <BLANKLINE> can be used as a special sequence to signify a
          # blank line, unless the DONT_ACCEPT_BLANKLINE flag is used.
          if not (optionflags & DONT_ACCEPT_BLANKLINE):
              # Replace <BLANKLINE> in want with a blank line.
              want = re.sub('(?m)^%s\s*?$' % re.escape(BLANKLINE_MARKER),
                            '', want)
              # If a line in got contains only spaces, then remove the
              # spaces.
              got = re.sub('(?m)^\s*?$', '', got)
              if got == want:
                  return True
  
          # This flag causes doctest to ignore any differences in the
          # contents of whitespace strings.  Note that this can be used
          # in conjunction with the ELLIPSIS flag.
          if optionflags & NORMALIZE_WHITESPACE:
              got = ' '.join(got.split())
              want = ' '.join(want.split())
              if got == want:
                  return True
  
          # The ELLIPSIS flag says to let the sequence "..." in `want`
          # match any substring in `got`.
          if optionflags & ELLIPSIS:
              if _ellipsis_match(want, got):
                  return True
  
          # We didn't find any match; return false.
          return False
  
      # Should we do a fancy diff?
      def _do_a_fancy_diff(self, want, got, optionflags):
          # Not unless they asked for a fancy diff.
          if not optionflags & (REPORT_UDIFF |
                                REPORT_CDIFF |
                                REPORT_NDIFF):
              return False
  
          # If expected output uses ellipsis, a meaningful fancy diff is
          # too hard ... or maybe not.  In two real-life failures Tim saw,
          # a diff was a major help anyway, so this is commented out.
          # [todo] _ellipsis_match() knows which pieces do and don't match,
          # and could be the basis for a kick-ass diff in this case.
          ##if optionflags & ELLIPSIS and ELLIPSIS_MARKER in want:
          ##    return False
  
          # ndiff does intraline difference marking, so can be useful even
          # for 1-line differences.
          if optionflags & REPORT_NDIFF:
              return True
  
          # The other diff types need at least a few lines to be helpful.
          return want.count('\n') > 2 and got.count('\n') > 2
  
      def output_difference(self, example, got, optionflags):
          """
          Return a string describing the differences between the
          expected output for a given example (`example`) and the actual
          output (`got`).  `optionflags` is the set of option flags used
          to compare `want` and `got`.
          """
          want = example.want
          # If <BLANKLINE>s are being used, then replace blank lines
          # with <BLANKLINE> in the actual output string.
          if not (optionflags & DONT_ACCEPT_BLANKLINE):
              got = re.sub('(?m)^[ ]*(?=\n)', BLANKLINE_MARKER, got)
  
          # Check if we should use diff.
          if self._do_a_fancy_diff(want, got, optionflags):
              # Split want & got into lines.
              want_lines = want.splitlines(keepends=True)
              got_lines = got.splitlines(keepends=True)
              # Use difflib to find their differences.
              if optionflags & REPORT_UDIFF:
                  diff = difflib.unified_diff(want_lines, got_lines, n=2)
                  diff = list(diff)[2:] # strip the diff header
                  kind = 'unified diff with -expected +actual'
              elif optionflags & REPORT_CDIFF:
                  diff = difflib.context_diff(want_lines, got_lines, n=2)
                  diff = list(diff)[2:] # strip the diff header
                  kind = 'context diff with expected followed by actual'
              elif optionflags & REPORT_NDIFF:
                  engine = difflib.Differ(charjunk=difflib.IS_CHARACTER_JUNK)
                  diff = list(engine.compare(want_lines, got_lines))
                  kind = 'ndiff with -expected +actual'
              else:
                  assert 0, 'Bad diff option'
              # Remove trailing whitespace on diff output.
              diff = [line.rstrip() + '\n' for line in diff]
              return 'Differences (%s):\n' % kind + _indent(''.join(diff))
  
          # If we're not using diff, then simply list the expected
          # output followed by the actual output.
          if want and got:
              return 'Expected:\n%sGot:\n%s' % (_indent(want), _indent(got))
          elif want:
              return 'Expected:\n%sGot nothing\n' % _indent(want)
          elif got:
              return 'Expected nothing\nGot:\n%s' % _indent(got)
          else:
              return 'Expected nothing\nGot nothing\n'
  
  class DocTestFailure(Exception):
      """A DocTest example has failed in debugging mode.
  
      The exception instance has variables:
  
      - test: the DocTest object being run
  
      - example: the Example object that failed
  
      - got: the actual output
      """
      def __init__(self, test, example, got):
          self.test = test
          self.example = example
          self.got = got
  
      def __str__(self):
          return str(self.test)
  
  class UnexpectedException(Exception):
      """A DocTest example has encountered an unexpected exception
  
      The exception instance has variables:
  
      - test: the DocTest object being run
  
      - example: the Example object that failed
  
      - exc_info: the exception info
      """
      def __init__(self, test, example, exc_info):
          self.test = test
          self.example = example
          self.exc_info = exc_info
  
      def __str__(self):
          return str(self.test)
  
  class DebugRunner(DocTestRunner):
      r"""Run doc tests but raise an exception as soon as there is a failure.
  
         If an unexpected exception occurs, an UnexpectedException is raised.
         It contains the test, the example, and the original exception:
  
           >>> runner = DebugRunner(verbose=False)
           >>> test = DocTestParser().get_doctest('>>> raise KeyError\n42',
           ...                                    {}, 'foo', 'foo.py', 0)
           >>> try:
           ...     runner.run(test)
           ... except UnexpectedException as f:
           ...     failure = f
  
           >>> failure.test is test
           True
  
           >>> failure.example.want
           '42\n'
  
           >>> exc_info = failure.exc_info
           >>> raise exc_info[1] # Already has the traceback
           Traceback (most recent call last):
           ...
           KeyError
  
         We wrap the original exception to give the calling application
         access to the test and example information.
  
         If the output doesn't match, then a DocTestFailure is raised:
  
           >>> test = DocTestParser().get_doctest('''
           ...      >>> x = 1
           ...      >>> x
           ...      2
           ...      ''', {}, 'foo', 'foo.py', 0)
  
           >>> try:
           ...    runner.run(test)
           ... except DocTestFailure as f:
           ...    failure = f
  
         DocTestFailure objects provide access to the test:
  
           >>> failure.test is test
           True
  
         As well as to the example:
  
           >>> failure.example.want
           '2\n'
  
         and the actual output:
  
           >>> failure.got
           '1\n'
  
         If a failure or error occurs, the globals are left intact:
  
           >>> del test.globs['__builtins__']
           >>> test.globs
           {'x': 1}
  
           >>> test = DocTestParser().get_doctest('''
           ...      >>> x = 2
           ...      >>> raise KeyError
           ...      ''', {}, 'foo', 'foo.py', 0)
  
           >>> runner.run(test)
           Traceback (most recent call last):
           ...
           doctest.UnexpectedException: <DocTest foo from foo.py:0 (2 examples)>
  
           >>> del test.globs['__builtins__']
           >>> test.globs
           {'x': 2}
  
         But the globals are cleared if there is no error:
  
           >>> test = DocTestParser().get_doctest('''
           ...      >>> x = 2
           ...      ''', {}, 'foo', 'foo.py', 0)
  
           >>> runner.run(test)
           TestResults(failed=0, attempted=1)
  
           >>> test.globs
           {}
  
         """
  
      def run(self, test, compileflags=None, out=None, clear_globs=True):
          r = DocTestRunner.run(self, test, compileflags, out, False)
          if clear_globs:
              test.globs.clear()
          return r
  
      def report_unexpected_exception(self, out, test, example, exc_info):
          raise UnexpectedException(test, example, exc_info)
  
      def report_failure(self, out, test, example, got):
          raise DocTestFailure(test, example, got)
  
  ######################################################################
  ## 6. Test Functions
  ######################################################################
  # These should be backwards compatible.
  
  # For backward compatibility, a global instance of a DocTestRunner
  # class, updated by testmod.
  master = None
  
  def testmod(m=None, name=None, globs=None, verbose=None,
              report=True, optionflags=0, extraglobs=None,
              raise_on_error=False, exclude_empty=False):
      """m=None, name=None, globs=None, verbose=None, report=True,
         optionflags=0, extraglobs=None, raise_on_error=False,
         exclude_empty=False
  
      Test examples in docstrings in functions and classes reachable
      from module m (or the current module if m is not supplied), starting
      with m.__doc__.
  
      Also test examples reachable from dict m.__test__ if it exists and is
      not None.  m.__test__ maps names to functions, classes and strings;
      function and class docstrings are tested even if the name is private;
      strings are tested directly, as if they were docstrings.
  
      Return (#failures, #tests).
  
      See help(doctest) for an overview.
  
      Optional keyword arg "name" gives the name of the module; by default
      use m.__name__.
  
      Optional keyword arg "globs" gives a dict to be used as the globals
      when executing examples; by default, use m.__dict__.  A copy of this
      dict is actually used for each docstring, so that each docstring's
      examples start with a clean slate.
  
      Optional keyword arg "extraglobs" gives a dictionary that should be
      merged into the globals that are used to execute examples.  By
      default, no extra globals are used.  This is new in 2.4.
  
      Optional keyword arg "verbose" prints lots of stuff if true, prints
      only failures if false; by default, it's true iff "-v" is in sys.argv.
  
      Optional keyword arg "report" prints a summary at the end when true,
      else prints nothing at the end.  In verbose mode, the summary is
      detailed, else very brief (in fact, empty if all tests passed).
  
      Optional keyword arg "optionflags" or's together module constants,
      and defaults to 0.  This is new in 2.3.  Possible values (see the
      docs for details):
  
          DONT_ACCEPT_TRUE_FOR_1
          DONT_ACCEPT_BLANKLINE
          NORMALIZE_WHITESPACE
          ELLIPSIS
          SKIP
          IGNORE_EXCEPTION_DETAIL
          REPORT_UDIFF
          REPORT_CDIFF
          REPORT_NDIFF
          REPORT_ONLY_FIRST_FAILURE
  
      Optional keyword arg "raise_on_error" raises an exception on the
      first unexpected exception or failure. This allows failures to be
      post-mortem debugged.
  
      Advanced tomfoolery:  testmod runs methods of a local instance of
      class doctest.Tester, then merges the results into (or creates)
      global Tester instance doctest.master.  Methods of doctest.master
      can be called directly too, if you want to do something unusual.
      Passing report=0 to testmod is especially useful then, to delay
      displaying a summary.  Invoke doctest.master.summarize(verbose)
      when you're done fiddling.
      """
      global master
  
      # If no module was given, then use __main__.
      if m is None:
          # DWA - m will still be None if this wasn't invoked from the command
          # line, in which case the following TypeError is about as good an error
          # as we should expect
          m = sys.modules.get('__main__')
  
      # Check that we were actually given a module.
      if not inspect.ismodule(m):
          raise TypeError("testmod: module required; %r" % (m,))
  
      # If no name was given, then use the module's name.
      if name is None:
          name = m.__name__
  
      # Find, parse, and run all tests in the given module.
      finder = DocTestFinder(exclude_empty=exclude_empty)
  
      if raise_on_error:
          runner = DebugRunner(verbose=verbose, optionflags=optionflags)
      else:
          runner = DocTestRunner(verbose=verbose, optionflags=optionflags)
  
      for test in finder.find(m, name, globs=globs, extraglobs=extraglobs):
          runner.run(test)
  
      if report:
          runner.summarize()
  
      if master is None:
          master = runner
      else:
          master.merge(runner)
  
      return TestResults(runner.failures, runner.tries)
  
  def testfile(filename, module_relative=True, name=None, package=None,
               globs=None, verbose=None, report=True, optionflags=0,
               extraglobs=None, raise_on_error=False, parser=DocTestParser(),
               encoding=None):
      """
      Test examples in the given file.  Return (#failures, #tests).
  
      Optional keyword arg "module_relative" specifies how filenames
      should be interpreted:
  
        - If "module_relative" is True (the default), then "filename"
           specifies a module-relative path.  By default, this path is
           relative to the calling module's directory; but if the
           "package" argument is specified, then it is relative to that
           package.  To ensure os-independence, "filename" should use
           "/" characters to separate path segments, and should not
           be an absolute path (i.e., it may not begin with "/").
  
        - If "module_relative" is False, then "filename" specifies an
          os-specific path.  The path may be absolute or relative (to
          the current working directory).
  
      Optional keyword arg "name" gives the name of the test; by default
      use the file's basename.
  
      Optional keyword argument "package" is a Python package or the
      name of a Python package whose directory should be used as the
      base directory for a module relative filename.  If no package is
      specified, then the calling module's directory is used as the base
      directory for module relative filenames.  It is an error to
      specify "package" if "module_relative" is False.
  
      Optional keyword arg "globs" gives a dict to be used as the globals
      when executing examples; by default, use {}.  A copy of this dict
      is actually used for each docstring, so that each docstring's
      examples start with a clean slate.
  
      Optional keyword arg "extraglobs" gives a dictionary that should be
      merged into the globals that are used to execute examples.  By
      default, no extra globals are used.
  
      Optional keyword arg "verbose" prints lots of stuff if true, prints
      only failures if false; by default, it's true iff "-v" is in sys.argv.
  
      Optional keyword arg "report" prints a summary at the end when true,
      else prints nothing at the end.  In verbose mode, the summary is
      detailed, else very brief (in fact, empty if all tests passed).
  
      Optional keyword arg "optionflags" or's together module constants,
      and defaults to 0.  Possible values (see the docs for details):
  
          DONT_ACCEPT_TRUE_FOR_1
          DONT_ACCEPT_BLANKLINE
          NORMALIZE_WHITESPACE
          ELLIPSIS
          SKIP
          IGNORE_EXCEPTION_DETAIL
          REPORT_UDIFF
          REPORT_CDIFF
          REPORT_NDIFF
          REPORT_ONLY_FIRST_FAILURE
  
      Optional keyword arg "raise_on_error" raises an exception on the
      first unexpected exception or failure. This allows failures to be
      post-mortem debugged.
  
      Optional keyword arg "parser" specifies a DocTestParser (or
      subclass) that should be used to extract tests from the files.
  
      Optional keyword arg "encoding" specifies an encoding that should
      be used to convert the file to unicode.
  
      Advanced tomfoolery:  testmod runs methods of a local instance of
      class doctest.Tester, then merges the results into (or creates)
      global Tester instance doctest.master.  Methods of doctest.master
      can be called directly too, if you want to do something unusual.
      Passing report=0 to testmod is especially useful then, to delay
      displaying a summary.  Invoke doctest.master.summarize(verbose)
      when you're done fiddling.
      """
      global master
  
      if package and not module_relative:
          raise ValueError("Package may only be specified for module-"
                           "relative paths.")
  
      # Relativize the path
      text, filename = _load_testfile(filename, package, module_relative,
                                      encoding or "utf-8")
  
      # If no name was given, then use the file's name.
      if name is None:
          name = os.path.basename(filename)
  
      # Assemble the globals.
      if globs is None:
          globs = {}
      else:
          globs = globs.copy()
      if extraglobs is not None:
          globs.update(extraglobs)
      if '__name__' not in globs:
          globs['__name__'] = '__main__'
  
      if raise_on_error:
          runner = DebugRunner(verbose=verbose, optionflags=optionflags)
      else:
          runner = DocTestRunner(verbose=verbose, optionflags=optionflags)
  
      # Read the file, convert it to a test, and run it.
      test = parser.get_doctest(text, globs, name, filename, 0)
      runner.run(test)
  
      if report:
          runner.summarize()
  
      if master is None:
          master = runner
      else:
          master.merge(runner)
  
      return TestResults(runner.failures, runner.tries)
  
  def run_docstring_examples(f, globs, verbose=False, name="NoName",
                             compileflags=None, optionflags=0):
      """
      Test examples in the given object's docstring (`f`), using `globs`
      as globals.  Optional argument `name` is used in failure messages.
      If the optional argument `verbose` is true, then generate output
      even if there are no failures.
  
      `compileflags` gives the set of flags that should be used by the
      Python compiler when running the examples.  If not specified, then
      it will default to the set of future-import flags that apply to
      `globs`.
  
      Optional keyword arg `optionflags` specifies options for the
      testing and output.  See the documentation for `testmod` for more
      information.
      """
      # Find, parse, and run all tests in the given module.
      finder = DocTestFinder(verbose=verbose, recurse=False)
      runner = DocTestRunner(verbose=verbose, optionflags=optionflags)
      for test in finder.find(f, name, globs=globs):
          runner.run(test, compileflags=compileflags)
  
  ######################################################################
  ## 7. Unittest Support
  ######################################################################
  
  _unittest_reportflags = 0
  
  def set_unittest_reportflags(flags):
      """Sets the unittest option flags.
  
      The old flag is returned so that a runner could restore the old
      value if it wished to:
  
        >>> import doctest
        >>> old = doctest._unittest_reportflags
        >>> doctest.set_unittest_reportflags(REPORT_NDIFF |
        ...                          REPORT_ONLY_FIRST_FAILURE) == old
        True
  
        >>> doctest._unittest_reportflags == (REPORT_NDIFF |
        ...                                   REPORT_ONLY_FIRST_FAILURE)
        True
  
      Only reporting flags can be set:
  
        >>> doctest.set_unittest_reportflags(ELLIPSIS)
        Traceback (most recent call last):
        ...
        ValueError: ('Only reporting flags allowed', 8)
  
        >>> doctest.set_unittest_reportflags(old) == (REPORT_NDIFF |
        ...                                   REPORT_ONLY_FIRST_FAILURE)
        True
      """
      global _unittest_reportflags
  
      if (flags & REPORTING_FLAGS) != flags:
          raise ValueError("Only reporting flags allowed", flags)
      old = _unittest_reportflags
      _unittest_reportflags = flags
      return old
  
  
  class DocTestCase(unittest.TestCase):
  
      def __init__(self, test, optionflags=0, setUp=None, tearDown=None,
                   checker=None):
  
          unittest.TestCase.__init__(self)
          self._dt_optionflags = optionflags
          self._dt_checker = checker
          self._dt_test = test
          self._dt_setUp = setUp
          self._dt_tearDown = tearDown
  
      def setUp(self):
          test = self._dt_test
  
          if self._dt_setUp is not None:
              self._dt_setUp(test)
  
      def tearDown(self):
          test = self._dt_test
  
          if self._dt_tearDown is not None:
              self._dt_tearDown(test)
  
          test.globs.clear()
  
      def runTest(self):
          test = self._dt_test
          old = sys.stdout
          new = StringIO()
          optionflags = self._dt_optionflags
  
          if not (optionflags & REPORTING_FLAGS):
              # The option flags don't include any reporting flags,
              # so add the default reporting flags
              optionflags |= _unittest_reportflags
  
          runner = DocTestRunner(optionflags=optionflags,
                                 checker=self._dt_checker, verbose=False)
  
          try:
              runner.DIVIDER = "-"*70
              failures, tries = runner.run(
                  test, out=new.write, clear_globs=False)
          finally:
              sys.stdout = old
  
          if failures:
              raise self.failureException(self.format_failure(new.getvalue()))
  
      def format_failure(self, err):
          test = self._dt_test
          if test.lineno is None:
              lineno = 'unknown line number'
          else:
              lineno = '%s' % test.lineno
          lname = '.'.join(test.name.split('.')[-1:])
          return ('Failed doctest test for %s\n'
                  '  File "%s", line %s, in %s\n\n%s'
                  % (test.name, test.filename, lineno, lname, err)
                  )
  
      def debug(self):
          r"""Run the test case without results and without catching exceptions
  
             The unit test framework includes a debug method on test cases
             and test suites to support post-mortem debugging.  The test code
             is run in such a way that errors are not caught.  This way a
             caller can catch the errors and initiate post-mortem debugging.
  
             The DocTestCase provides a debug method that raises
             UnexpectedException errors if there is an unexpected
             exception:
  
               >>> test = DocTestParser().get_doctest('>>> raise KeyError\n42',
               ...                {}, 'foo', 'foo.py', 0)
               >>> case = DocTestCase(test)
               >>> try:
               ...     case.debug()
               ... except UnexpectedException as f:
               ...     failure = f
  
             The UnexpectedException contains the test, the example, and
             the original exception:
  
               >>> failure.test is test
               True
  
               >>> failure.example.want
               '42\n'
  
               >>> exc_info = failure.exc_info
               >>> raise exc_info[1] # Already has the traceback
               Traceback (most recent call last):
               ...
               KeyError
  
             If the output doesn't match, then a DocTestFailure is raised:
  
               >>> test = DocTestParser().get_doctest('''
               ...      >>> x = 1
               ...      >>> x
               ...      2
               ...      ''', {}, 'foo', 'foo.py', 0)
               >>> case = DocTestCase(test)
  
               >>> try:
               ...    case.debug()
               ... except DocTestFailure as f:
               ...    failure = f
  
             DocTestFailure objects provide access to the test:
  
               >>> failure.test is test
               True
  
             As well as to the example:
  
               >>> failure.example.want
               '2\n'
  
             and the actual output:
  
               >>> failure.got
               '1\n'
  
             """
  
          self.setUp()
          runner = DebugRunner(optionflags=self._dt_optionflags,
                               checker=self._dt_checker, verbose=False)
          runner.run(self._dt_test, clear_globs=False)
          self.tearDown()
  
      def id(self):
          return self._dt_test.name
  
      def __eq__(self, other):
          if type(self) is not type(other):
              return NotImplemented
  
          return self._dt_test == other._dt_test and \
                 self._dt_optionflags == other._dt_optionflags and \
                 self._dt_setUp == other._dt_setUp and \
                 self._dt_tearDown == other._dt_tearDown and \
                 self._dt_checker == other._dt_checker
  
      def __hash__(self):
          return hash((self._dt_optionflags, self._dt_setUp, self._dt_tearDown,
                       self._dt_checker))
  
      def __repr__(self):
          name = self._dt_test.name.split('.')
          return "%s (%s)" % (name[-1], '.'.join(name[:-1]))
  
      __str__ = __repr__
  
      def shortDescription(self):
          return "Doctest: " + self._dt_test.name
  
  class SkipDocTestCase(DocTestCase):
      def __init__(self, module):
          self.module = module
          DocTestCase.__init__(self, None)
  
      def setUp(self):
          self.skipTest("DocTestSuite will not work with -O2 and above")
  
      def test_skip(self):
          pass
  
      def shortDescription(self):
          return "Skipping tests from %s" % self.module.__name__
  
      __str__ = shortDescription
  
  
  class _DocTestSuite(unittest.TestSuite):
  
      def _removeTestAtIndex(self, index):
          pass
  
  
  def DocTestSuite(module=None, globs=None, extraglobs=None, test_finder=None,
                   **options):
      """
      Convert doctest tests for a module to a unittest test suite.
  
      This converts each documentation string in a module that
      contains doctest tests to a unittest test case.  If any of the
      tests in a doc string fail, then the test case fails.  An exception
      is raised showing the name of the file containing the test and a
      (sometimes approximate) line number.
  
      The `module` argument provides the module to be tested.  The argument
      can be either a module or a module name.
  
      If no argument is given, the calling module is used.
  
      A number of options may be provided as keyword arguments:
  
      setUp
        A set-up function.  This is called before running the
        tests in each file. The setUp function will be passed a DocTest
        object.  The setUp function can access the test globals as the
        globs attribute of the test passed.
  
      tearDown
        A tear-down function.  This is called after running the
        tests in each file.  The tearDown function will be passed a DocTest
        object.  The tearDown function can access the test globals as the
        globs attribute of the test passed.
  
      globs
        A dictionary containing initial global variables for the tests.
  
      optionflags
         A set of doctest option flags expressed as an integer.
      """
  
      if test_finder is None:
          test_finder = DocTestFinder()
  
      module = _normalize_module(module)
      tests = test_finder.find(module, globs=globs, extraglobs=extraglobs)
  
      if not tests and sys.flags.optimize >=2:
          # Skip doctests when running with -O2
          suite = _DocTestSuite()
          suite.addTest(SkipDocTestCase(module))
          return suite
  
      tests.sort()
      suite = _DocTestSuite()
  
      for test in tests:
          if len(test.examples) == 0:
              continue
          if not test.filename:
              filename = module.__file__
              if filename[-4:] == ".pyc":
                  filename = filename[:-1]
              test.filename = filename
          suite.addTest(DocTestCase(test, **options))
  
      return suite
  
  class DocFileCase(DocTestCase):
  
      def id(self):
          return '_'.join(self._dt_test.name.split('.'))
  
      def __repr__(self):
          return self._dt_test.filename
      __str__ = __repr__
  
      def format_failure(self, err):
          return ('Failed doctest test for %s\n  File "%s", line 0\n\n%s'
                  % (self._dt_test.name, self._dt_test.filename, err)
                  )
  
  def DocFileTest(path, module_relative=True, package=None,
                  globs=None, parser=DocTestParser(),
                  encoding=None, **options):
      if globs is None:
          globs = {}
      else:
          globs = globs.copy()
  
      if package and not module_relative:
          raise ValueError("Package may only be specified for module-"
                           "relative paths.")
  
      # Relativize the path.
      doc, path = _load_testfile(path, package, module_relative,
                                 encoding or "utf-8")
  
      if "__file__" not in globs:
          globs["__file__"] = path
  
      # Find the file and read it.
      name = os.path.basename(path)
  
      # Convert it to a test, and wrap it in a DocFileCase.
      test = parser.get_doctest(doc, globs, name, path, 0)
      return DocFileCase(test, **options)
  
  def DocFileSuite(*paths, **kw):
      """A unittest suite for one or more doctest files.
  
      The path to each doctest file is given as a string; the
      interpretation of that string depends on the keyword argument
      "module_relative".
  
      A number of options may be provided as keyword arguments:
  
      module_relative
        If "module_relative" is True, then the given file paths are
        interpreted as os-independent module-relative paths.  By
        default, these paths are relative to the calling module's
        directory; but if the "package" argument is specified, then
        they are relative to that package.  To ensure os-independence,
        "filename" should use "/" characters to separate path
        segments, and may not be an absolute path (i.e., it may not
        begin with "/").
  
        If "module_relative" is False, then the given file paths are
        interpreted as os-specific paths.  These paths may be absolute
        or relative (to the current working directory).
  
      package
        A Python package or the name of a Python package whose directory
        should be used as the base directory for module relative paths.
        If "package" is not specified, then the calling module's
        directory is used as the base directory for module relative
        filenames.  It is an error to specify "package" if
        "module_relative" is False.
  
      setUp
        A set-up function.  This is called before running the
        tests in each file. The setUp function will be passed a DocTest
        object.  The setUp function can access the test globals as the
        globs attribute of the test passed.
  
      tearDown
        A tear-down function.  This is called after running the
        tests in each file.  The tearDown function will be passed a DocTest
        object.  The tearDown function can access the test globals as the
        globs attribute of the test passed.
  
      globs
        A dictionary containing initial global variables for the tests.
  
      optionflags
        A set of doctest option flags expressed as an integer.
  
      parser
        A DocTestParser (or subclass) that should be used to extract
        tests from the files.
  
      encoding
        An encoding that will be used to convert the files to unicode.
      """
      suite = _DocTestSuite()
  
      # We do this here so that _normalize_module is called at the right
      # level.  If it were called in DocFileTest, then this function
      # would be the caller and we might guess the package incorrectly.
      if kw.get('module_relative', True):
          kw['package'] = _normalize_module(kw.get('package'))
  
      for path in paths:
          suite.addTest(DocFileTest(path, **kw))
  
      return suite
  
  ######################################################################
  ## 8. Debugging Support
  ######################################################################
  
  def script_from_examples(s):
      r"""Extract script from text with examples.
  
         Converts text with examples to a Python script.  Example input is
         converted to regular code.  Example output and all other words
         are converted to comments:
  
         >>> text = '''
         ...       Here are examples of simple math.
         ...
         ...           Python has super accurate integer addition
         ...
         ...           >>> 2 + 2
         ...           5
         ...
         ...           And very friendly error messages:
         ...
         ...           >>> 1/0
         ...           To Infinity
         ...           And
         ...           Beyond
         ...
         ...           You can use logic if you want:
         ...
         ...           >>> if 0:
         ...           ...    blah
         ...           ...    blah
         ...           ...
         ...
         ...           Ho hum
         ...           '''
  
         >>> print(script_from_examples(text))
         # Here are examples of simple math.
         #
         #     Python has super accurate integer addition
         #
         2 + 2
         # Expected:
         ## 5
         #
         #     And very friendly error messages:
         #
         1/0
         # Expected:
         ## To Infinity
         ## And
         ## Beyond
         #
         #     You can use logic if you want:
         #
         if 0:
            blah
            blah
         #
         #     Ho hum
         <BLANKLINE>
         """
      output = []
      for piece in DocTestParser().parse(s):
          if isinstance(piece, Example):
              # Add the example's source code (strip trailing NL)
              output.append(piece.source[:-1])
              # Add the expected output:
              want = piece.want
              if want:
                  output.append('# Expected:')
                  output += ['## '+l for l in want.split('\n')[:-1]]
          else:
              # Add non-example text.
              output += [_comment_line(l)
                         for l in piece.split('\n')[:-1]]
  
      # Trim junk on both ends.
      while output and output[-1] == '#':
          output.pop()
      while output and output[0] == '#':
          output.pop(0)
      # Combine the output, and return it.
      # Add a courtesy newline to prevent exec from choking (see bug #1172785)
      return '\n'.join(output) + '\n'
  
  def testsource(module, name):
      """Extract the test sources from a doctest docstring as a script.
  
      Provide the module (or dotted name of the module) containing the
      test to be debugged and the name (within the module) of the object
      with the doc string with tests to be debugged.
      """
      module = _normalize_module(module)
      tests = DocTestFinder().find(module)
      test = [t for t in tests if t.name == name]
      if not test:
          raise ValueError(name, "not found in tests")
      test = test[0]
      testsrc = script_from_examples(test.docstring)
      return testsrc
  
  def debug_src(src, pm=False, globs=None):
      """Debug a single doctest docstring, in argument `src`'"""
      testsrc = script_from_examples(src)
      debug_script(testsrc, pm, globs)
  
  def debug_script(src, pm=False, globs=None):
      "Debug a test script.  `src` is the script, as a string."
      import pdb
  
      if globs:
          globs = globs.copy()
      else:
          globs = {}
  
      if pm:
          try:
              exec(src, globs, globs)
          except:
              print(sys.exc_info()[1])
              p = pdb.Pdb(nosigint=True)
              p.reset()
              p.interaction(None, sys.exc_info()[2])
      else:
          pdb.Pdb(nosigint=True).run("exec(%r)" % src, globs, globs)
  
  def debug(module, name, pm=False):
      """Debug a single doctest docstring.
  
      Provide the module (or dotted name of the module) containing the
      test to be debugged and the name (within the module) of the object
      with the docstring with tests to be debugged.
      """
      module = _normalize_module(module)
      testsrc = testsource(module, name)
      debug_script(testsrc, pm, module.__dict__)
  
  ######################################################################
  ## 9. Example Usage
  ######################################################################
  class _TestClass:
      """
      A pointless class, for sanity-checking of docstring testing.
  
      Methods:
          square()
          get()
  
      >>> _TestClass(13).get() + _TestClass(-12).get()
      1
      >>> hex(_TestClass(13).square().get())
      '0xa9'
      """
  
      def __init__(self, val):
          """val -> _TestClass object with associated value val.
  
          >>> t = _TestClass(123)
          >>> print(t.get())
          123
          """
  
          self.val = val
  
      def square(self):
          """square() -> square TestClass's associated value
  
          >>> _TestClass(13).square().get()
          169
          """
  
          self.val = self.val ** 2
          return self
  
      def get(self):
          """get() -> return TestClass's associated value.
  
          >>> x = _TestClass(-42)
          >>> print(x.get())
          -42
          """
  
          return self.val
  
  __test__ = {"_TestClass": _TestClass,
              "string": r"""
                        Example of a string object, searched as-is.
                        >>> x = 1; y = 2
                        >>> x + y, x * y
                        (3, 2)
                        """,
  
              "bool-int equivalence": r"""
                                      In 2.2, boolean expressions displayed
                                      0 or 1.  By default, we still accept
                                      them.  This can be disabled by passing
                                      DONT_ACCEPT_TRUE_FOR_1 to the new
                                      optionflags argument.
                                      >>> 4 == 4
                                      1
                                      >>> 4 == 4
                                      True
                                      >>> 4 > 4
                                      0
                                      >>> 4 > 4
                                      False
                                      """,
  
              "blank lines": r"""
                  Blank lines can be marked with <BLANKLINE>:
                      >>> print('foo\n\nbar\n')
                      foo
                      <BLANKLINE>
                      bar
                      <BLANKLINE>
              """,
  
              "ellipsis": r"""
                  If the ellipsis flag is used, then '...' can be used to
                  elide substrings in the desired output:
                      >>> print(list(range(1000))) #doctest: +ELLIPSIS
                      [0, 1, 2, ..., 999]
              """,
  
              "whitespace normalization": r"""
                  If the whitespace normalization flag is used, then
                  differences in whitespace are ignored.
                      >>> print(list(range(30))) #doctest: +NORMALIZE_WHITESPACE
                      [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
                       15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26,
                       27, 28, 29]
              """,
             }
  
  
  def _test():
      parser = argparse.ArgumentParser(description="doctest runner")
      parser.add_argument('-v', '--verbose', action='store_true', default=False,
                          help='print very verbose output for all tests')
      parser.add_argument('-o', '--option', action='append',
                          choices=OPTIONFLAGS_BY_NAME.keys(), default=[],
                          help=('specify a doctest option flag to apply'
                                ' to the test run; may be specified more'
                                ' than once to apply multiple options'))
      parser.add_argument('-f', '--fail-fast', action='store_true',
                          help=('stop running tests after first failure (this'
                                ' is a shorthand for -o FAIL_FAST, and is'
                                ' in addition to any other -o options)'))
      parser.add_argument('file', nargs='+',
                          help='file containing the tests to run')
      args = parser.parse_args()
      testfiles = args.file
      # Verbose used to be handled by the "inspect argv" magic in DocTestRunner,
      # but since we are using argparse we are passing it manually now.
      verbose = args.verbose
      options = 0
      for option in args.option:
          options |= OPTIONFLAGS_BY_NAME[option]
      if args.fail_fast:
          options |= FAIL_FAST
      for filename in testfiles:
          if filename.endswith(".py"):
              # It is a module -- insert its dir into sys.path and try to
              # import it. If it is part of a package, that possibly
              # won't work because of package imports.
              dirname, filename = os.path.split(filename)
              sys.path.insert(0, dirname)
              m = __import__(filename[:-3])
              del sys.path[0]
              failures, _ = testmod(m, verbose=verbose, optionflags=options)
          else:
              failures, _ = testfile(filename, module_relative=False,
                                       verbose=verbose, optionflags=options)
          if failures:
              return 1
      return 0
  
  
  if __name__ == "__main__":
      sys.exit(_test())
  