text: """Utilities for processing .test files containing test case descriptions."""
  
  import os.path
  import os
  import tempfile
  import posixpath
  import re
  from os import remove, rmdir
  import shutil
  from abc import abstractmethod
  
  import pytest  # type: ignore  # no pytest in typeshed
  from typing import List, Tuple, Set, Optional, Iterator, Any, Dict, NamedTuple, Union
  
  from mypy.test.config import test_data_prefix, test_temp_dir
  
  root_dir = os.path.normpath(os.path.join(os.path.dirname(__file__), '..', '..'))
  
  # File modify/create operation: copy module contents from source_path.
  UpdateFile = NamedTuple('UpdateFile', [('module', str),
                                         ('source_path', str),
                                         ('target_path', str)])
  
  # File delete operation: delete module file.
  DeleteFile = NamedTuple('DeleteFile', [('module', str),
                                         ('path', str)])
  
  FileOperation = Union[UpdateFile, DeleteFile]
  
  
  def parse_test_cases(parent: 'DataSuiteCollector', suite: 'DataSuite',
                       path: str) -> Iterator['DataDrivenTestCase']:
      """Parse a single file from suite with test case descriptions.
  
      NB: this function and DataDrivenTestCase were shared between the
      myunit and pytest codepaths -- if something looks redundant,
      that's likely the reason.
      """
      base_path = suite.base_path
      if suite.native_sep:
          join = os.path.join
      else:
          join = posixpath.join  # type: ignore
      with open(path, encoding='utf-8') as f:
          lst = f.readlines()
      for i in range(len(lst)):
          lst[i] = lst[i].rstrip('\n')
      p = parse_test_data(lst, path)
  
      # Process the parsed items. Each item has a header of form [id args],
      # optionally followed by lines of text.
      i = 0
      while i < len(p):
          ok = False
          i0 = i
          if p[i].id == 'case':
              i += 1
  
              files = []  # type: List[Tuple[str, str]] # path and contents
              output_files = []  # type: List[Tuple[str, str]] # path and contents for output files
              tcout = []  # type: List[str]  # Regular output errors
              tcout2 = {}  # type: Dict[int, List[str]]  # Output errors for incremental, runs 2+
              deleted_paths = {}  # type: Dict[int, Set[str]]  # from run number of paths
              stale_modules = {}  # type: Dict[int, Set[str]]  # from run number to module names
              rechecked_modules = {}  # type: Dict[ int, Set[str]]  # from run number module names
              triggered = []  # type: List[str]  # Active triggers (one line per incremental step)
              while i < len(p) and p[i].id != 'case':
                  if p[i].id == 'file' or p[i].id == 'outfile':
                      # Record an extra file needed for the test case.
                      arg = p[i].arg
                      assert arg is not None
                      contents = '\n'.join(p[i].data)
                      contents = expand_variables(contents)
                      file_entry = (join(base_path, arg), contents)
                      if p[i].id == 'file':
                          files.append(file_entry)
                      elif p[i].id == 'outfile':
                          output_files.append(file_entry)
                  elif p[i].id in ('builtins', 'builtins_py2'):
                      # Use an alternative stub file for the builtins module.
                      arg = p[i].arg
                      assert arg is not None
                      mpath = join(os.path.dirname(path), arg)
                      if p[i].id == 'builtins':
                          fnam = 'builtins.pyi'
                      else:
                          # Python 2
                          fnam = '__builtin__.pyi'
                      with open(mpath) as f:
                          files.append((join(base_path, fnam), f.read()))
                  elif p[i].id == 'typing':
                      # Use an alternative stub file for the typing module.
                      arg = p[i].arg
                      assert arg is not None
                      src_path = join(os.path.dirname(path), arg)
                      with open(src_path) as f:
                          files.append((join(base_path, 'typing.pyi'), f.read()))
                  elif re.match(r'stale[0-9]*$', p[i].id):
                      if p[i].id == 'stale':
                          passnum = 1
                      else:
                          passnum = int(p[i].id[len('stale'):])
                          assert passnum > 0
                      arg = p[i].arg
                      if arg is None:
                          stale_modules[passnum] = set()
                      else:
                          stale_modules[passnum] = {item.strip() for item in arg.split(',')}
                  elif re.match(r'rechecked[0-9]*$', p[i].id):
                      if p[i].id == 'rechecked':
                          passnum = 1
                      else:
                          passnum = int(p[i].id[len('rechecked'):])
                      arg = p[i].arg
                      if arg is None:
                          rechecked_modules[passnum] = set()
                      else:
                          rechecked_modules[passnum] = {item.strip() for item in arg.split(',')}
                  elif p[i].id == 'delete':
                      # File to delete during a multi-step test case
                      arg = p[i].arg
                      assert arg is not None
                      m = re.match(r'(.*)\.([0-9]+)$', arg)
                      assert m, 'Invalid delete section: {}'.format(arg)
                      num = int(m.group(2))
                      assert num >= 2, "Can't delete during step {}".format(num)
                      full = join(base_path, m.group(1))
                      deleted_paths.setdefault(num, set()).add(full)
                  elif p[i].id == 'out' or p[i].id == 'out1':
                      tcout = p[i].data
                      tcout = [expand_variables(line) for line in tcout]
                      if os.path.sep == '\\':
                          tcout = [fix_win_path(line) for line in tcout]
                      ok = True
                  elif re.match(r'out[0-9]*$', p[i].id):
                      passnum = int(p[i].id[3:])
                      assert passnum > 1
                      output = p[i].data
                      output = [expand_variables(line) for line in output]
                      if suite.native_sep and os.path.sep == '\\':
                          output = [fix_win_path(line) for line in output]
                      tcout2[passnum] = output
                      ok = True
                  elif p[i].id == 'triggered' and p[i].arg is None:
                      triggered = p[i].data
                  else:
                      raise ValueError(
                          'Invalid section header {} in {} at line {}'.format(
                              p[i].id, path, p[i].line))
                  i += 1
  
              for passnum in stale_modules.keys():
                  if passnum not in rechecked_modules:
                      # If the set of rechecked modules isn't specified, make it the same as the set
                      # of modules with a stale public interface.
                      rechecked_modules[passnum] = stale_modules[passnum]
                  if (passnum in stale_modules
                          and passnum in rechecked_modules
                          and not stale_modules[passnum].issubset(rechecked_modules[passnum])):
                      raise ValueError(
                          ('Stale modules after pass {} must be a subset of rechecked '
                           'modules ({}:{})').format(passnum, path, p[i0].line))
  
              if not suite.required_out_section:
                  ok = True
  
              if ok:
                  input = p[i0].data
                  expand_errors(input, tcout, 'main')
                  for file_path, contents in files:
                      expand_errors(contents.split('\n'), tcout, file_path)
                  lastline = p[i].line if i < len(p) else p[i - 1].line + 9999
                  arg0 = p[i0].arg
                  assert arg0 is not None
                  case_name = add_test_name_suffix(arg0, suite.test_name_suffix)
                  skip = arg0.endswith('-skip')
                  if skip:
                      case_name = case_name[:-len('-skip')]
                  yield DataDrivenTestCase(case_name, parent, skip, input, tcout, tcout2, path,
                                           p[i0].line, lastline,
                                           files, output_files, stale_modules,
                                           rechecked_modules, deleted_paths, suite.native_sep,
                                           triggered)
          if not ok:
              raise ValueError(
                  '{}, line {}: Error in test case description'.format(
                      path, p[i0].line))
  
  
  class DataDrivenTestCase(pytest.Item):  # type: ignore  # inheriting from Any
      """Holds parsed data-driven test cases, and handles directory setup and teardown."""
  
      # TODO: only create files on setup, not during parsing
  
      input = None  # type: List[str]
      output = None  # type: List[str]  # Output for the first pass
      output2 = None  # type: Dict[int, List[str]]  # Output for runs 2+, indexed by run number
  
      file = ''
      line = 0
  
      # (file path, file content) tuples
      files = None  # type: List[Tuple[str, str]]
      expected_stale_modules = None  # type: Dict[int, Set[str]]
      expected_rechecked_modules = None  # type: Dict[int, Set[str]]
  
      # Files/directories to clean up after test case; (is directory, path) tuples
      clean_up = None  # type: List[Tuple[bool, str]]
  
      def __init__(self,
                   name: str,
                   parent: 'DataSuiteCollector',
                   skip: bool,
                   input: List[str],
                   output: List[str],
                   output2: Dict[int, List[str]],
                   file: str,
                   line: int,
                   lastline: int,
                   files: List[Tuple[str, str]],
                   output_files: List[Tuple[str, str]],
                   expected_stale_modules: Dict[int, Set[str]],
                   expected_rechecked_modules: Dict[int, Set[str]],
                   deleted_paths: Dict[int, Set[str]],
                   native_sep: bool = False,
                   triggered: Optional[List[str]] = None,
                   ) -> None:
  
          super().__init__(name, parent)
          self.skip = skip
          self.old_cwd = None  # type: Optional[str]
          self.tmpdir = None  # type: Optional[tempfile.TemporaryDirectory[str]]
          self.input = input
          self.output = output
          self.output2 = output2
          self.lastline = lastline
          self.file = file
          self.line = line
          self.files = files
          self.output_files = output_files
          self.expected_stale_modules = expected_stale_modules
          self.expected_rechecked_modules = expected_rechecked_modules
          self.deleted_paths = deleted_paths
          self.native_sep = native_sep
          self.triggered = triggered or []
  
      def runtest(self) -> None:
          if self.skip:
              pytest.skip()
          suite = self.parent.obj()
          suite.setup()
          suite.run_case(self)
  
      def setup(self) -> None:
          self.old_cwd = os.getcwd()
          self.tmpdir = tempfile.TemporaryDirectory(prefix='mypy-test-')
          os.chdir(self.tmpdir.name)
          os.mkdir('tmp')
          encountered_files = set()
          self.clean_up = []
          for paths in self.deleted_paths.values():
              for path in paths:
                  self.clean_up.append((False, path))
                  encountered_files.add(path)
          for path, content in self.files:
              dir = os.path.dirname(path)
              for d in self.add_dirs(dir):
                  self.clean_up.append((True, d))
              with open(path, 'w') as f:
                  f.write(content)
              if path not in encountered_files:
                  self.clean_up.append((False, path))
                  encountered_files.add(path)
              if re.search(r'\.[2-9]$', path):
                  # Make sure new files introduced in the second and later runs are accounted for
                  renamed_path = path[:-2]
                  if renamed_path not in encountered_files:
                      encountered_files.add(renamed_path)
                      self.clean_up.append((False, renamed_path))
          for path, _ in self.output_files:
              # Create directories for expected output and mark them to be cleaned up at the end
              # of the test case.
              dir = os.path.dirname(path)
              for d in self.add_dirs(dir):
                  self.clean_up.append((True, d))
              self.clean_up.append((False, path))
  
      def add_dirs(self, dir: str) -> List[str]:
          """Add all subdirectories required to create dir.
  
          Return an array of the created directories in the order of creation.
          """
          if dir == '' or os.path.isdir(dir):
              return []
          else:
              dirs = self.add_dirs(os.path.dirname(dir)) + [dir]
              os.mkdir(dir)
              return dirs
  
      def teardown(self) -> None:
          # First remove files.
          for is_dir, path in reversed(self.clean_up):
              if not is_dir:
                  try:
                      remove(path)
                  except FileNotFoundError:
                      # Breaking early using Ctrl+C may happen before file creation. Also, some
                      # files may be deleted by a test case.
                      pass
          # Then remove directories.
          for is_dir, path in reversed(self.clean_up):
              if is_dir:
                  pycache = os.path.join(path, '__pycache__')
                  if os.path.isdir(pycache):
                      shutil.rmtree(pycache)
                  # As a somewhat nasty hack, ignore any dirs with .mypy_cache in the path,
                  # to allow test cases to intentionally corrupt the cache without provoking
                  # the test suite when there are still files left over.
                  # (Looking at / should be fine on windows because these are paths specified
                  # in the test cases.)
                  if '/.mypy_cache' in path:
                      continue
                  try:
                      rmdir(path)
                  except OSError as error:
                      print(' ** Error removing directory %s -- contents:' % path)
                      for item in os.listdir(path):
                          print('  ', item)
                      # Most likely, there are some files in the
                      # directory. Use rmtree to nuke the directory, but
                      # fail the test case anyway, since this seems like
                      # a bug in a test case -- we shouldn't leave
                      # garbage lying around. By nuking the directory,
                      # the next test run hopefully passes.
                      path = error.filename
                      # Be defensive -- only call rmtree if we're sure we aren't removing anything
                      # valuable.
                      if path.startswith(test_temp_dir + '/') and os.path.isdir(path):
                          shutil.rmtree(path)
                      raise
          assert self.old_cwd is not None and self.tmpdir is not None, \
              "test was not properly set up"
          os.chdir(self.old_cwd)
          try:
              self.tmpdir.cleanup()
          except OSError:
              pass
          self.old_cwd = None
          self.tmpdir = None
  
      def reportinfo(self) -> Tuple[str, int, str]:
          return self.file, self.line, self.name
  
      def repr_failure(self, excinfo: Any) -> str:
          if excinfo.errisinstance(SystemExit):
              # We assume that before doing exit() (which raises SystemExit) we've printed
              # enough context about what happened so that a stack trace is not useful.
              # In particular, uncaught exceptions during semantic analysis or type checking
              # call exit() and they already print out a stack trace.
              excrepr = excinfo.exconly()
          else:
              self.parent._prunetraceback(excinfo)
              excrepr = excinfo.getrepr(style='short')
  
          return "data: {}:{}:\n{}".format(self.file, self.line, excrepr)
  
      def find_steps(self) -> List[List[FileOperation]]:
          """Return a list of descriptions of file operations for each incremental step.
  
          The first list item corresponds to the first incremental step, the second for the
          second step, etc. Each operation can either be a file modification/creation (UpdateFile)
          or deletion (DeleteFile).
  
          Defaults to having two steps if there aern't any operations.
          """
          steps = {}  # type: Dict[int, List[FileOperation]]
          for path, _ in self.files:
              m = re.match(r'.*\.([0-9]+)$', path)
              if m:
                  num = int(m.group(1))
                  assert num >= 2
                  target_path = re.sub(r'\.[0-9]+$', '', path)
                  module = module_from_path(target_path)
                  operation = UpdateFile(module, path, target_path)
                  steps.setdefault(num, []).append(operation)
          for num, paths in self.deleted_paths.items():
              assert num >= 2
              for path in paths:
                  module = module_from_path(path)
                  steps.setdefault(num, []).append(DeleteFile(module, path))
          max_step = max(steps) if steps else 2
          return [steps.get(num, []) for num in range(2, max_step + 1)]
  
  
  def module_from_path(path: str) -> str:
      path = re.sub(r'\.pyi?$', '', path)
      # We can have a mix of Unix-style and Windows-style separators.
      parts = re.split(r'[/\\]', path)
      assert parts[0] == test_temp_dir
      del parts[0]
      module = '.'.join(parts)
      module = re.sub(r'\.__init__$', '', module)
      return module
  
  
  class TestItem:
      """Parsed test caseitem.
  
      An item is of the form
        [id arg]
        .. data ..
      """
  
      id = ''
      arg = ''  # type: Optional[str]
  
      # Text data, array of 8-bit strings
      data = None  # type: List[str]
  
      file = ''
      line = 0  # Line number in file
  
      def __init__(self, id: str, arg: Optional[str], data: List[str], file: str,
                   line: int) -> None:
          self.id = id
          self.arg = arg
          self.data = data
          self.file = file
          self.line = line
  
  
  def parse_test_data(l: List[str], fnam: str) -> List[TestItem]:
      """Parse a list of lines that represent a sequence of test items."""
  
      ret = []  # type: List[TestItem]
      data = []  # type: List[str]
  
      id = None  # type: Optional[str]
      arg = None  # type: Optional[str]
  
      i = 0
      i0 = 0
      while i < len(l):
          s = l[i].strip()
  
          if l[i].startswith('[') and s.endswith(']') and not s.startswith('[['):
              if id:
                  data = collapse_line_continuation(data)
                  data = strip_list(data)
                  ret.append(TestItem(id, arg, strip_list(data), fnam, i0 + 1))
              i0 = i
              id = s[1:-1]
              arg = None
              if ' ' in id:
                  arg = id[id.index(' ') + 1:]
                  id = id[:id.index(' ')]
              data = []
          elif l[i].startswith('[['):
              data.append(l[i][1:])
          elif not l[i].startswith('--'):
              data.append(l[i])
          elif l[i].startswith('----'):
              data.append(l[i][2:])
          i += 1
  
      # Process the last item.
      if id:
          data = collapse_line_continuation(data)
          data = strip_list(data)
          ret.append(TestItem(id, arg, data, fnam, i0 + 1))
  
      return ret
  
  
  def strip_list(l: List[str]) -> List[str]:
      """Return a stripped copy of l.
  
      Strip whitespace at the end of all lines, and strip all empty
      lines from the end of the array.
      """
  
      r = []  # type: List[str]
      for s in l:
          # Strip spaces at end of line
          r.append(re.sub(r'\s+$', '', s))
  
      while len(r) > 0 and r[-1] == '':
          r.pop()
  
      return r
  
  
  def collapse_line_continuation(l: List[str]) -> List[str]:
      r = []  # type: List[str]
      cont = False
      for s in l:
          ss = re.sub(r'\\$', '', s)
          if cont:
              r[-1] += re.sub('^ +', '', ss)
          else:
              r.append(ss)
          cont = s.endswith('\\')
      return r
  
  
  def expand_variables(s: str) -> str:
      return s.replace('<ROOT>', root_dir)
  
  
  def expand_errors(input: List[str], output: List[str], fnam: str) -> None:
      """Transform comments such as '# E: message' or
      '# E:3: message' in input.
  
      The result is lines like 'fnam:line: error: message'.
      """
  
      for i in range(len(input)):
          # The first in the split things isn't a comment
          for possible_err_comment in input[i].split(' # ')[1:]:
              m = re.search(
                  '^([ENW]):((?P<col>\d+):)? (?P<message>.*)$',
                  possible_err_comment.strip())
              if m:
                  if m.group(1) == 'E':
                      severity = 'error'
                  elif m.group(1) == 'N':
                      severity = 'note'
                  elif m.group(1) == 'W':
                      severity = 'warning'
                  col = m.group('col')
                  if col is None:
                      output.append(
                          '{}:{}: {}: {}'.format(fnam, i + 1, severity, m.group('message')))
                  else:
                      output.append('{}:{}:{}: {}: {}'.format(
                          fnam, i + 1, col, severity, m.group('message')))
  
  
  def fix_win_path(line: str) -> str:
      r"""Changes Windows paths to Linux paths in error messages.
  
      E.g. foo\bar.py -> foo/bar.py.
      """
      line = line.replace(root_dir, root_dir.replace('\\', '/'))
      m = re.match(r'^([\S/]+):(\d+:)?(\s+.*)', line)
      if not m:
          return line
      else:
          filename, lineno, message = m.groups()
          return '{}:{}{}'.format(filename.replace('\\', '/'),
                                  lineno or '', message)
  
  
  def fix_cobertura_filename(line: str) -> str:
      r"""Changes filename paths to Linux paths in Cobertura output files.
  
      E.g. filename="pkg\subpkg\a.py" -> filename="pkg/subpkg/a.py".
      """
      m = re.search(r'<class .* filename="(?P<filename>.*?)"', line)
      if not m:
          return line
      return '{}{}{}'.format(line[:m.start(1)],
                             m.group('filename').replace('\\', '/'),
                             line[m.end(1):])
  
  
  ##
  #
  # pytest setup
  #
  ##
  
  
  # This function name is special to pytest.  See
  # https://docs.pytest.org/en/latest/reference.html#initialization-hooks
  def pytest_addoption(parser: Any) -> None:
      group = parser.getgroup('mypy')
      group.addoption('--update-data', action='store_true', default=False,
                      help='Update test data to reflect actual output'
                           ' (supported only for certain tests)')
  
  
  # This function name is special to pytest.  See
  # http://doc.pytest.org/en/latest/writing_plugins.html#collection-hooks
  def pytest_pycollect_makeitem(collector: Any, name: str,
                                obj: object) -> 'Optional[Any]':
      """Called by pytest on each object in modules configured in conftest.py files.
  
      collector is pytest.Collector, returns Optional[pytest.Class]
      """
      if isinstance(obj, type):
          # Only classes derived from DataSuite contain test cases, not the DataSuite class itself
          if issubclass(obj, DataSuite) and obj is not DataSuite:
              # Non-None result means this obj is a test case.
              # The collect method of the returned DataSuiteCollector instance will be called later,
              # with self.obj being obj.
              return DataSuiteCollector(name, parent=collector)
      return None
  
  
  class DataSuiteCollector(pytest.Class):  # type: ignore  # inheriting from Any
      def collect(self) -> Iterator[pytest.Item]:  # type: ignore
          """Called by pytest on each of the object returned from pytest_pycollect_makeitem"""
  
          # obj is the object for which pytest_pycollect_makeitem returned self.
          suite = self.obj  # type: DataSuite
          for f in suite.files:
              yield from parse_test_cases(self, suite, os.path.join(suite.data_prefix, f))
  
  
  def add_test_name_suffix(name: str, suffix: str) -> str:
      # Find magic suffix of form "-foobar" (used for things like "-skip").
      m = re.search(r'-[-A-Za-z0-9]+$', name)
      if m:
          # Insert suite-specific test name suffix before the magic suffix
          # which must be the last thing in the test case name since we
          # are using endswith() checks.
          magic_suffix = m.group(0)
          return name[:-len(magic_suffix)] + suffix + magic_suffix
      else:
          return name + suffix
  
  
  def is_incremental(testcase: DataDrivenTestCase) -> bool:
      return 'incremental' in testcase.name.lower() or 'incremental' in testcase.file
  
  
  def has_stable_flags(testcase: DataDrivenTestCase) -> bool:
      if any(re.match(r'# flags[2-9]:', line) for line in testcase.input):
          return False
      for filename, contents in testcase.files:
          if os.path.basename(filename).startswith('mypy.ini.'):
              return False
      return True
  
  
  class DataSuite:
      # option fields - class variables
      files = None  # type: List[str]
  
      base_path = test_temp_dir
  
      # Allow external users of the test code to override the data prefix
      data_prefix = test_data_prefix
  
      required_out_section = False
  
      native_sep = False
  
      # Name suffix automatically added to each test case in the suite (can be
      # used to distinguish test cases in suites that share data files)
      test_name_suffix = ''
  
      def setup(self) -> None:
          """Setup fixtures (ad-hoc)"""
          pass
  
      @abstractmethod
      def run_case(self, testcase: DataDrivenTestCase) -> None:
          raise NotImplementedError
  