text: """Rewrite assertion AST to produce nice error messages."""
  import ast
  import errno
  import functools
  import importlib.abc
  import importlib.machinery
  import importlib.util
  import io
  import itertools
  import marshal
  import os
  import struct
  import sys
  import tokenize
  import types
  from pathlib import Path
  from pathlib import PurePath
  from typing import Callable
  from typing import Dict
  from typing import IO
  from typing import Iterable
  from typing import List
  from typing import Optional
  from typing import Sequence
  from typing import Set
  from typing import Tuple
  from typing import TYPE_CHECKING
  from typing import Union
  
  from _pytest._io.saferepr import DEFAULT_REPR_MAX_SIZE
  from _pytest._io.saferepr import saferepr
  from _pytest._version import version
  from _pytest.assertion import util
  from _pytest.assertion.util import (  # noqa: F401
      format_explanation as _format_explanation,
  )
  from _pytest.config import Config
  from _pytest.main import Session
  from _pytest.pathlib import absolutepath
  from _pytest.pathlib import fnmatch_ex
  from _pytest.stash import StashKey
  
  if TYPE_CHECKING:
      from _pytest.assertion import AssertionState
  
  
  assertstate_key = StashKey["AssertionState"]()
  
  
  # pytest caches rewritten pycs in pycache dirs
  PYTEST_TAG = f"{sys.implementation.cache_tag}-pytest-{version}"
  PYC_EXT = ".py" + (__debug__ and "c" or "o")
  PYC_TAIL = "." + PYTEST_TAG + PYC_EXT
  
  
  class AssertionRewritingHook(importlib.abc.MetaPathFinder, importlib.abc.Loader):
      """PEP302/PEP451 import hook which rewrites asserts."""
  
      def __init__(self, config: Config) -> None:
          self.config = config
          try:
              self.fnpats = config.getini("python_files")
          except ValueError:
              self.fnpats = ["test_*.py", "*_test.py"]
          self.session: Optional[Session] = None
          self._rewritten_names: Set[str] = set()
          self._must_rewrite: Set[str] = set()
          # flag to guard against trying to rewrite a pyc file while we are already writing another pyc file,
          # which might result in infinite recursion (#3506)
          self._writing_pyc = False
          self._basenames_to_check_rewrite = {"conftest"}
          self._marked_for_rewrite_cache: Dict[str, bool] = {}
          self._session_paths_checked = False
  
      def set_session(self, session: Optional[Session]) -> None:
          self.session = session
          self._session_paths_checked = False
  
      # Indirection so we can mock calls to find_spec originated from the hook during testing
      _find_spec = importlib.machinery.PathFinder.find_spec
  
      def find_spec(
          self,
          name: str,
          path: Optional[Sequence[Union[str, bytes]]] = None,
          target: Optional[types.ModuleType] = None,
      ) -> Optional[importlib.machinery.ModuleSpec]:
          if self._writing_pyc:
              return None
          state = self.config.stash[assertstate_key]
          if self._early_rewrite_bailout(name, state):
              return None
          state.trace("find_module called for: %s" % name)
  
          # Type ignored because mypy is confused about the `self` binding here.
          spec = self._find_spec(name, path)  # type: ignore
          if (
              # the import machinery could not find a file to import
              spec is None
              # this is a namespace package (without `__init__.py`)
              # there's nothing to rewrite there
              # python3.6: `namespace`
              # python3.7+: `None`
              or spec.origin == "namespace"
              or spec.origin is None
              # we can only rewrite source files
              or not isinstance(spec.loader, importlib.machinery.SourceFileLoader)
              # if the file doesn't exist, we can't rewrite it
              or not os.path.exists(spec.origin)
          ):
              return None
          else:
              fn = spec.origin
  
          if not self._should_rewrite(name, fn, state):
              return None
  
          return importlib.util.spec_from_file_location(
              name,
              fn,
              loader=self,
              submodule_search_locations=spec.submodule_search_locations,
          )
  
      def create_module(
          self, spec: importlib.machinery.ModuleSpec
      ) -> Optional[types.ModuleType]:
          return None  # default behaviour is fine
  
      def exec_module(self, module: types.ModuleType) -> None:
          assert module.__spec__ is not None
          assert module.__spec__.origin is not None
          fn = Path(module.__spec__.origin)
          state = self.config.stash[assertstate_key]
  
          self._rewritten_names.add(module.__name__)
  
          # The requested module looks like a test file, so rewrite it. This is
          # the most magical part of the process: load the source, rewrite the
          # asserts, and load the rewritten source. We also cache the rewritten
          # module code in a special pyc. We must be aware of the possibility of
          # concurrent pytest processes rewriting and loading pycs. To avoid
          # tricky race conditions, we maintain the following invariant: The
          # cached pyc is always a complete, valid pyc. Operations on it must be
          # atomic. POSIX's atomic rename comes in handy.
          write = not sys.dont_write_bytecode
          cache_dir = get_cache_dir(fn)
          if write:
              ok = try_makedirs(cache_dir)
              if not ok:
                  write = False
                  state.trace(f"read only directory: {cache_dir}")
  
          cache_name = fn.name[:-3] + PYC_TAIL
          pyc = cache_dir / cache_name
          # Notice that even if we're in a read-only directory, I'm going
          # to check for a cached pyc. This may not be optimal...
          co = _read_pyc(fn, pyc, state.trace)
          if co is None:
              state.trace(f"rewriting {fn!r}")
              source_stat, co = _rewrite_test(fn, self.config)
              if write:
                  self._writing_pyc = True
                  try:
                      _write_pyc(state, co, source_stat, pyc)
                  finally:
                      self._writing_pyc = False
          else:
              state.trace(f"found cached rewritten pyc for {fn}")
          exec(co, module.__dict__)
  
      def _early_rewrite_bailout(self, name: str, state: "AssertionState") -> bool:
          """A fast way to get out of rewriting modules.
  
          Profiling has shown that the call to PathFinder.find_spec (inside of
          the find_spec from this class) is a major slowdown, so, this method
          tries to filter what we're sure won't be rewritten before getting to
          it.
          """
          if self.session is not None and not self._session_paths_checked:
              self._session_paths_checked = True
              for initial_path in self.session._initialpaths:
                  # Make something as c:/projects/my_project/path.py ->
                  #     ['c:', 'projects', 'my_project', 'path.py']
                  parts = str(initial_path).split(os.path.sep)
                  # add 'path' to basenames to be checked.
                  self._basenames_to_check_rewrite.add(os.path.splitext(parts[-1])[0])
  
          # Note: conftest already by default in _basenames_to_check_rewrite.
          parts = name.split(".")
          if parts[-1] in self._basenames_to_check_rewrite:
              return False
  
          # For matching the name it must be as if it was a filename.
          path = PurePath(os.path.sep.join(parts) + ".py")
  
          for pat in self.fnpats:
              # if the pattern contains subdirectories ("tests/**.py" for example) we can't bail out based
              # on the name alone because we need to match against the full path
              if os.path.dirname(pat):
                  return False
              if fnmatch_ex(pat, path):
                  return False
  
          if self._is_marked_for_rewrite(name, state):
              return False
  
          state.trace(f"early skip of rewriting module: {name}")
          return True
  
      def _should_rewrite(self, name: str, fn: str, state: "AssertionState") -> bool:
          # always rewrite conftest files
          if os.path.basename(fn) == "conftest.py":
              state.trace(f"rewriting conftest file: {fn!r}")
              return True
  
          if self.session is not None:
              if self.session.isinitpath(absolutepath(fn)):
                  state.trace(f"matched test file (was specified on cmdline): {fn!r}")
                  return True
  
          # modules not passed explicitly on the command line are only
          # rewritten if they match the naming convention for test files
          fn_path = PurePath(fn)
          for pat in self.fnpats:
              if fnmatch_ex(pat, fn_path):
                  state.trace(f"matched test file {fn!r}")
                  return True
  
          return self._is_marked_for_rewrite(name, state)
  
      def _is_marked_for_rewrite(self, name: str, state: "AssertionState") -> bool:
          try:
              return self._marked_for_rewrite_cache[name]
          except KeyError:
              for marked in self._must_rewrite:
                  if name == marked or name.startswith(marked + "."):
                      state.trace(f"matched marked file {name!r} (from {marked!r})")
                      self._marked_for_rewrite_cache[name] = True
                      return True
  
              self._marked_for_rewrite_cache[name] = False
              return False
  
      def mark_rewrite(self, *names: str) -> None:
          """Mark import names as needing to be rewritten.
  
          The named module or package as well as any nested modules will
          be rewritten on import.
          """
          already_imported = (
              set(names).intersection(sys.modules).difference(self._rewritten_names)
          )
          for name in already_imported:
              mod = sys.modules[name]
              if not AssertionRewriter.is_rewrite_disabled(
                  mod.__doc__ or ""
              ) and not isinstance(mod.__loader__, type(self)):
                  self._warn_already_imported(name)
          self._must_rewrite.update(names)
          self._marked_for_rewrite_cache.clear()
  
      def _warn_already_imported(self, name: str) -> None:
          from _pytest.warning_types import PytestAssertRewriteWarning
  
          self.config.issue_config_time_warning(
              PytestAssertRewriteWarning(
                  "Module already imported so cannot be rewritten: %s" % name
              ),
              stacklevel=5,
          )
  
      def get_data(self, pathname: Union[str, bytes]) -> bytes:
          """Optional PEP302 get_data API."""
          with open(pathname, "rb") as f:
              return f.read()
  
  
  def _write_pyc_fp(
      fp: IO[bytes], source_stat: os.stat_result, co: types.CodeType
  ) -> None:
      # Technically, we don't have to have the same pyc format as
      # (C)Python, since these "pycs" should never be seen by builtin
      # import. However, there's little reason to deviate.
      fp.write(importlib.util.MAGIC_NUMBER)
      # https://www.python.org/dev/peps/pep-0552/
      if sys.version_info >= (3, 7):
          flags = b"\x00\x00\x00\x00"
          fp.write(flags)
      # as of now, bytecode header expects 32-bit numbers for size and mtime (#4903)
      mtime = int(source_stat.st_mtime) & 0xFFFFFFFF
      size = source_stat.st_size & 0xFFFFFFFF
      # "<LL" stands for 2 unsigned longs, little-endian.
      fp.write(struct.pack("<LL", mtime, size))
      fp.write(marshal.dumps(co))
  
  
  if sys.platform == "win32":
      from atomicwrites import atomic_write
  
      def _write_pyc(
          state: "AssertionState",
          co: types.CodeType,
          source_stat: os.stat_result,
          pyc: Path,
      ) -> bool:
          try:
              with atomic_write(os.fspath(pyc), mode="wb", overwrite=True) as fp:
                  _write_pyc_fp(fp, source_stat, co)
          except OSError as e:
              state.trace(f"error writing pyc file at {pyc}: {e}")
              # we ignore any failure to write the cache file
              # there are many reasons, permission-denied, pycache dir being a
              # file etc.
              return False
          return True
  
  
  else:
  
      def _write_pyc(
          state: "AssertionState",
          co: types.CodeType,
          source_stat: os.stat_result,
          pyc: Path,
      ) -> bool:
          proc_pyc = f"{pyc}.{os.getpid()}"
          try:
              fp = open(proc_pyc, "wb")
          except OSError as e:
              state.trace(f"error writing pyc file at {proc_pyc}: errno={e.errno}")
              return False
  
          try:
              _write_pyc_fp(fp, source_stat, co)
              os.rename(proc_pyc, os.fspath(pyc))
          except OSError as e:
              state.trace(f"error writing pyc file at {pyc}: {e}")
              # we ignore any failure to write the cache file
              # there are many reasons, permission-denied, pycache dir being a
              # file etc.
              return False
          finally:
              fp.close()
          return True
  
  
  def _rewrite_test(fn: Path, config: Config) -> Tuple[os.stat_result, types.CodeType]:
      """Read and rewrite *fn* and return the code object."""
      fn_ = os.fspath(fn)
      stat = os.stat(fn_)
      with open(fn_, "rb") as f:
          source = f.read()
      tree = ast.parse(source, filename=fn_)
      rewrite_asserts(tree, source, fn_, config)
      co = compile(tree, fn_, "exec", dont_inherit=True)
      return stat, co
  
  
  def _read_pyc(
      source: Path, pyc: Path, trace: Callable[[str], None] = lambda x: None
  ) -> Optional[types.CodeType]:
      """Possibly read a pytest pyc containing rewritten code.
  
      Return rewritten code if successful or None if not.
      """
      try:
          fp = open(os.fspath(pyc), "rb")
      except OSError:
          return None
      with fp:
          # https://www.python.org/dev/peps/pep-0552/
          has_flags = sys.version_info >= (3, 7)
          try:
              stat_result = os.stat(os.fspath(source))
              mtime = int(stat_result.st_mtime)
              size = stat_result.st_size
              data = fp.read(16 if has_flags else 12)
          except OSError as e:
              trace(f"_read_pyc({source}): OSError {e}")
              return None
          # Check for invalid or out of date pyc file.
          if len(data) != (16 if has_flags else 12):
              trace("_read_pyc(%s): invalid pyc (too short)" % source)
              return None
          if data[:4] != importlib.util.MAGIC_NUMBER:
              trace("_read_pyc(%s): invalid pyc (bad magic number)" % source)
              return None
          if has_flags and data[4:8] != b"\x00\x00\x00\x00":
              trace("_read_pyc(%s): invalid pyc (unsupported flags)" % source)
              return None
          mtime_data = data[8 if has_flags else 4 : 12 if has_flags else 8]
          if int.from_bytes(mtime_data, "little") != mtime & 0xFFFFFFFF:
              trace("_read_pyc(%s): out of date" % source)
              return None
          size_data = data[12 if has_flags else 8 : 16 if has_flags else 12]
          if int.from_bytes(size_data, "little") != size & 0xFFFFFFFF:
              trace("_read_pyc(%s): invalid pyc (incorrect size)" % source)
              return None
          try:
              co = marshal.load(fp)
          except Exception as e:
              trace(f"_read_pyc({source}): marshal.load error {e}")
              return None
          if not isinstance(co, types.CodeType):
              trace("_read_pyc(%s): not a code object" % source)
              return None
          return co
  
  
  def rewrite_asserts(
      mod: ast.Module,
      source: bytes,
      module_path: Optional[str] = None,
      config: Optional[Config] = None,
  ) -> None:
      """Rewrite the assert statements in mod."""
      AssertionRewriter(module_path, config, source).run(mod)
  
  
  def _saferepr(obj: object) -> str:
      r"""Get a safe repr of an object for assertion error messages.
  
      The assertion formatting (util.format_explanation()) requires
      newlines to be escaped since they are a special character for it.
      Normally assertion.util.format_explanation() does this but for a
      custom repr it is possible to contain one of the special escape
      sequences, especially '\n{' and '\n}' are likely to be present in
      JSON reprs.
      """
      maxsize = _get_maxsize_for_saferepr(util._config)
      return saferepr(obj, maxsize=maxsize).replace("\n", "\\n")
  
  
  def _get_maxsize_for_saferepr(config: Optional[Config]) -> Optional[int]:
      """Get `maxsize` configuration for saferepr based on the given config object."""
      verbosity = config.getoption("verbose") if config is not None else 0
      if verbosity >= 2:
          return None
      if verbosity >= 1:
          return DEFAULT_REPR_MAX_SIZE * 10
      return DEFAULT_REPR_MAX_SIZE
  
  
  def _format_assertmsg(obj: object) -> str:
      r"""Format the custom assertion message given.
  
      For strings this simply replaces newlines with '\n~' so that
      util.format_explanation() will preserve them instead of escaping
      newlines.  For other objects saferepr() is used first.
      """
      # reprlib appears to have a bug which means that if a string
      # contains a newline it gets escaped, however if an object has a
      # .__repr__() which contains newlines it does not get escaped.
      # However in either case we want to preserve the newline.
      replaces = [("\n", "\n~"), ("%", "%%")]
      if not isinstance(obj, str):
          obj = saferepr(obj)
          replaces.append(("\\n", "\n~"))
  
      for r1, r2 in replaces:
          obj = obj.replace(r1, r2)
  
      return obj
  
  
  def _should_repr_global_name(obj: object) -> bool:
      if callable(obj):
          return False
  
      try:
          return not hasattr(obj, "__name__")
      except Exception:
          return True
  
  
  def _format_boolop(explanations: Iterable[str], is_or: bool) -> str:
      explanation = "(" + (is_or and " or " or " and ").join(explanations) + ")"
      return explanation.replace("%", "%%")
  
  
  def _call_reprcompare(
      ops: Sequence[str],
      results: Sequence[bool],
      expls: Sequence[str],
      each_obj: Sequence[object],
  ) -> str:
      for i, res, expl in zip(range(len(ops)), results, expls):
          try:
              done = not res
          except Exception:
              done = True
          if done:
              break
      if util._reprcompare is not None:
          custom = util._reprcompare(ops[i], each_obj[i], each_obj[i + 1])
          if custom is not None:
              return custom
      return expl
  
  
  def _call_assertion_pass(lineno: int, orig: str, expl: str) -> None:
      if util._assertion_pass is not None:
          util._assertion_pass(lineno, orig, expl)
  
  
  def _check_if_assertion_pass_impl() -> bool:
      """Check if any plugins implement the pytest_assertion_pass hook
      in order not to generate explanation unecessarily (might be expensive)."""
      return True if util._assertion_pass else False
  
  
  UNARY_MAP = {ast.Not: "not %s", ast.Invert: "~%s", ast.USub: "-%s", ast.UAdd: "+%s"}
  
  BINOP_MAP = {
      ast.BitOr: "|",
      ast.BitXor: "^",
      ast.BitAnd: "&",
      ast.LShift: "<<",
      ast.RShift: ">>",
      ast.Add: "+",
      ast.Sub: "-",
      ast.Mult: "*",
      ast.Div: "/",
      ast.FloorDiv: "//",
      ast.Mod: "%%",  # escaped for string formatting
      ast.Eq: "==",
      ast.NotEq: "!=",
      ast.Lt: "<",
      ast.LtE: "<=",
      ast.Gt: ">",
      ast.GtE: ">=",
      ast.Pow: "**",
      ast.Is: "is",
      ast.IsNot: "is not",
      ast.In: "in",
      ast.NotIn: "not in",
      ast.MatMult: "@",
  }
  
  
  def set_location(node, lineno, col_offset):
      """Set node location information recursively."""
  
      def _fix(node, lineno, col_offset):
          if "lineno" in node._attributes:
              node.lineno = lineno
          if "col_offset" in node._attributes:
              node.col_offset = col_offset
          for child in ast.iter_child_nodes(node):
              _fix(child, lineno, col_offset)
  
      _fix(node, lineno, col_offset)
      return node
  
  
  @functools.lru_cache(maxsize=1)
  def _get_assertion_exprs(src: bytes) -> Dict[int, str]:
      """Return a mapping from {lineno: "assertion test expression"}."""
      ret: Dict[int, str] = {}
  
      depth = 0
      lines: List[str] = []
      assert_lineno: Optional[int] = None
      seen_lines: Set[int] = set()
  
      def _write_and_reset() -> None:
          nonlocal depth, lines, assert_lineno, seen_lines
          assert assert_lineno is not None
          ret[assert_lineno] = "".join(lines).rstrip().rstrip("\\")
          depth = 0
          lines = []
          assert_lineno = None
          seen_lines = set()
  
      tokens = tokenize.tokenize(io.BytesIO(src).readline)
      for tp, source, (lineno, offset), _, line in tokens:
          if tp == tokenize.NAME and source == "assert":
              assert_lineno = lineno
          elif assert_lineno is not None:
              # keep track of depth for the assert-message `,` lookup
              if tp == tokenize.OP and source in "([{":
                  depth += 1
              elif tp == tokenize.OP and source in ")]}":
                  depth -= 1
  
              if not lines:
                  lines.append(line[offset:])
                  seen_lines.add(lineno)
              # a non-nested comma separates the expression from the message
              elif depth == 0 and tp == tokenize.OP and source == ",":
                  # one line assert with message
                  if lineno in seen_lines and len(lines) == 1:
                      offset_in_trimmed = offset + len(lines[-1]) - len(line)
                      lines[-1] = lines[-1][:offset_in_trimmed]
                  # multi-line assert with message
                  elif lineno in seen_lines:
                      lines[-1] = lines[-1][:offset]
                  # multi line assert with escapd newline before message
                  else:
                      lines.append(line[:offset])
                  _write_and_reset()
              elif tp in {tokenize.NEWLINE, tokenize.ENDMARKER}:
                  _write_and_reset()
              elif lines and lineno not in seen_lines:
                  lines.append(line)
                  seen_lines.add(lineno)
  
      return ret
  
  
  class AssertionRewriter(ast.NodeVisitor):
      """Assertion rewriting implementation.
  
      The main entrypoint is to call .run() with an ast.Module instance,
      this will then find all the assert statements and rewrite them to
      provide intermediate values and a detailed assertion error.  See
      http://pybites.blogspot.be/2011/07/behind-scenes-of-pytests-new-assertion.html
      for an overview of how this works.
  
      The entry point here is .run() which will iterate over all the
      statements in an ast.Module and for each ast.Assert statement it
      finds call .visit() with it.  Then .visit_Assert() takes over and
      is responsible for creating new ast statements to replace the
      original assert statement: it rewrites the test of an assertion
      to provide intermediate values and replace it with an if statement
      which raises an assertion error with a detailed explanation in
      case the expression is false and calls pytest_assertion_pass hook
      if expression is true.
  
      For this .visit_Assert() uses the visitor pattern to visit all the
      AST nodes of the ast.Assert.test field, each visit call returning
      an AST node and the corresponding explanation string.  During this
      state is kept in several instance attributes:
  
      :statements: All the AST statements which will replace the assert
         statement.
  
      :variables: This is populated by .variable() with each variable
         used by the statements so that they can all be set to None at
         the end of the statements.
  
      :variable_counter: Counter to create new unique variables needed
         by statements.  Variables are created using .variable() and
         have the form of "@py_assert0".
  
      :expl_stmts: The AST statements which will be executed to get
         data from the assertion.  This is the code which will construct
         the detailed assertion message that is used in the AssertionError
         or for the pytest_assertion_pass hook.
  
      :explanation_specifiers: A dict filled by .explanation_param()
         with %-formatting placeholders and their corresponding
         expressions to use in the building of an assertion message.
         This is used by .pop_format_context() to build a message.
  
      :stack: A stack of the explanation_specifiers dicts maintained by
         .push_format_context() and .pop_format_context() which allows
         to build another %-formatted string while already building one.
  
      This state is reset on every new assert statement visited and used
      by the other visitors.
      """
  
      def __init__(
          self, module_path: Optional[str], config: Optional[Config], source: bytes
      ) -> None:
          super().__init__()
          self.module_path = module_path
          self.config = config
          if config is not None:
              self.enable_assertion_pass_hook = config.getini(
                  "enable_assertion_pass_hook"
              )
          else:
              self.enable_assertion_pass_hook = False
          self.source = source
  
      def run(self, mod: ast.Module) -> None:
          """Find all assert statements in *mod* and rewrite them."""
          if not mod.body:
              # Nothing to do.
              return
  
          # We'll insert some special imports at the top of the module, but after any
          # docstrings and __future__ imports, so first figure out where that is.
          doc = getattr(mod, "docstring", None)
          expect_docstring = doc is None
          if doc is not None and self.is_rewrite_disabled(doc):
              return
          pos = 0
          lineno = 1
          for item in mod.body:
              if (
                  expect_docstring
                  and isinstance(item, ast.Expr)
                  and isinstance(item.value, ast.Str)
              ):
                  doc = item.value.s
                  if self.is_rewrite_disabled(doc):
                      return
                  expect_docstring = False
              elif (
                  isinstance(item, ast.ImportFrom)
                  and item.level == 0
                  and item.module == "__future__"
              ):
                  pass
              else:
                  break
              pos += 1
          # Special case: for a decorated function, set the lineno to that of the
          # first decorator, not the `def`. Issue #4984.
          if isinstance(item, ast.FunctionDef) and item.decorator_list:
              lineno = item.decorator_list[0].lineno
          else:
              lineno = item.lineno
          # Now actually insert the special imports.
          if sys.version_info >= (3, 10):
              aliases = [
                  ast.alias("builtins", "@py_builtins", lineno=lineno, col_offset=0),
                  ast.alias(
                      "_pytest.assertion.rewrite",
                      "@pytest_ar",
                      lineno=lineno,
                      col_offset=0,
                  ),
              ]
          else:
              aliases = [
                  ast.alias("builtins", "@py_builtins"),
                  ast.alias("_pytest.assertion.rewrite", "@pytest_ar"),
              ]
          imports = [
              ast.Import([alias], lineno=lineno, col_offset=0) for alias in aliases
          ]
          mod.body[pos:pos] = imports
  
          # Collect asserts.
          nodes: List[ast.AST] = [mod]
          while nodes:
              node = nodes.pop()
              for name, field in ast.iter_fields(node):
                  if isinstance(field, list):
                      new: List[ast.AST] = []
                      for i, child in enumerate(field):
                          if isinstance(child, ast.Assert):
                              # Transform assert.
                              new.extend(self.visit(child))
                          else:
                              new.append(child)
                              if isinstance(child, ast.AST):
                                  nodes.append(child)
                      setattr(node, name, new)
                  elif (
                      isinstance(field, ast.AST)
                      # Don't recurse into expressions as they can't contain
                      # asserts.
                      and not isinstance(field, ast.expr)
                  ):
                      nodes.append(field)
  
      @staticmethod
      def is_rewrite_disabled(docstring: str) -> bool:
          return "PYTEST_DONT_REWRITE" in docstring
  
      def variable(self) -> str:
          """Get a new variable."""
          # Use a character invalid in python identifiers to avoid clashing.
          name = "@py_assert" + str(next(self.variable_counter))
          self.variables.append(name)
          return name
  
      def assign(self, expr: ast.expr) -> ast.Name:
          """Give *expr* a name."""
          name = self.variable()
          self.statements.append(ast.Assign([ast.Name(name, ast.Store())], expr))
          return ast.Name(name, ast.Load())
  
      def display(self, expr: ast.expr) -> ast.expr:
          """Call saferepr on the expression."""
          return self.helper("_saferepr", expr)
  
      def helper(self, name: str, *args: ast.expr) -> ast.expr:
          """Call a helper in this module."""
          py_name = ast.Name("@pytest_ar", ast.Load())
          attr = ast.Attribute(py_name, name, ast.Load())
          return ast.Call(attr, list(args), [])
  
      def builtin(self, name: str) -> ast.Attribute:
          """Return the builtin called *name*."""
          builtin_name = ast.Name("@py_builtins", ast.Load())
          return ast.Attribute(builtin_name, name, ast.Load())
  
      def explanation_param(self, expr: ast.expr) -> str:
          """Return a new named %-formatting placeholder for expr.
  
          This creates a %-formatting placeholder for expr in the
          current formatting context, e.g. ``%(py0)s``.  The placeholder
          and expr are placed in the current format context so that it
          can be used on the next call to .pop_format_context().
          """
          specifier = "py" + str(next(self.variable_counter))
          self.explanation_specifiers[specifier] = expr
          return "%(" + specifier + ")s"
  
      def push_format_context(self) -> None:
          """Create a new formatting context.
  
          The format context is used for when an explanation wants to
          have a variable value formatted in the assertion message.  In
          this case the value required can be added using
          .explanation_param().  Finally .pop_format_context() is used
          to format a string of %-formatted values as added by
          .explanation_param().
          """
          self.explanation_specifiers: Dict[str, ast.expr] = {}
          self.stack.append(self.explanation_specifiers)
  
      def pop_format_context(self, expl_expr: ast.expr) -> ast.Name:
          """Format the %-formatted string with current format context.
  
          The expl_expr should be an str ast.expr instance constructed from
          the %-placeholders created by .explanation_param().  This will
          add the required code to format said string to .expl_stmts and
          return the ast.Name instance of the formatted string.
          """
          current = self.stack.pop()
          if self.stack:
              self.explanation_specifiers = self.stack[-1]
          keys = [ast.Str(key) for key in current.keys()]
          format_dict = ast.Dict(keys, list(current.values()))
          form = ast.BinOp(expl_expr, ast.Mod(), format_dict)
          name = "@py_format" + str(next(self.variable_counter))
          if self.enable_assertion_pass_hook:
              self.format_variables.append(name)
          self.expl_stmts.append(ast.Assign([ast.Name(name, ast.Store())], form))
          return ast.Name(name, ast.Load())
  
      def generic_visit(self, node: ast.AST) -> Tuple[ast.Name, str]:
          """Handle expressions we don't have custom code for."""
          assert isinstance(node, ast.expr)
          res = self.assign(node)
          return res, self.explanation_param(self.display(res))
  
      def visit_Assert(self, assert_: ast.Assert) -> List[ast.stmt]:
          """Return the AST statements to replace the ast.Assert instance.
  
          This rewrites the test of an assertion to provide
          intermediate values and replace it with an if statement which
          raises an assertion error with a detailed explanation in case
          the expression is false.
          """
          if isinstance(assert_.test, ast.Tuple) and len(assert_.test.elts) >= 1:
              from _pytest.warning_types import PytestAssertRewriteWarning
              import warnings
  
              # TODO: This assert should not be needed.
              assert self.module_path is not None
              warnings.warn_explicit(
                  PytestAssertRewriteWarning(
                      "assertion is always true, perhaps remove parentheses?"
                  ),
                  category=None,
                  filename=os.fspath(self.module_path),
                  lineno=assert_.lineno,
              )
  
          self.statements: List[ast.stmt] = []
          self.variables: List[str] = []
          self.variable_counter = itertools.count()
  
          if self.enable_assertion_pass_hook:
              self.format_variables: List[str] = []
  
          self.stack: List[Dict[str, ast.expr]] = []
          self.expl_stmts: List[ast.stmt] = []
          self.push_format_context()
          # Rewrite assert into a bunch of statements.
          top_condition, explanation = self.visit(assert_.test)
  
          negation = ast.UnaryOp(ast.Not(), top_condition)
  
          if self.enable_assertion_pass_hook:  # Experimental pytest_assertion_pass hook
              msg = self.pop_format_context(ast.Str(explanation))
  
              # Failed
              if assert_.msg:
                  assertmsg = self.helper("_format_assertmsg", assert_.msg)
                  gluestr = "\n>assert "
              else:
                  assertmsg = ast.Str("")
                  gluestr = "assert "
              err_explanation = ast.BinOp(ast.Str(gluestr), ast.Add(), msg)
              err_msg = ast.BinOp(assertmsg, ast.Add(), err_explanation)
              err_name = ast.Name("AssertionError", ast.Load())
              fmt = self.helper("_format_explanation", err_msg)
              exc = ast.Call(err_name, [fmt], [])
              raise_ = ast.Raise(exc, None)
              statements_fail = []
              statements_fail.extend(self.expl_stmts)
              statements_fail.append(raise_)
  
              # Passed
              fmt_pass = self.helper("_format_explanation", msg)
              orig = _get_assertion_exprs(self.source)[assert_.lineno]
              hook_call_pass = ast.Expr(
                  self.helper(
                      "_call_assertion_pass",
                      ast.Num(assert_.lineno),
                      ast.Str(orig),
                      fmt_pass,
                  )
              )
              # If any hooks implement assert_pass hook
              hook_impl_test = ast.If(
                  self.helper("_check_if_assertion_pass_impl"),
                  self.expl_stmts + [hook_call_pass],
                  [],
              )
              statements_pass = [hook_impl_test]
  
              # Test for assertion condition
              main_test = ast.If(negation, statements_fail, statements_pass)
              self.statements.append(main_test)
              if self.format_variables:
                  variables = [
                      ast.Name(name, ast.Store()) for name in self.format_variables
                  ]
                  clear_format = ast.Assign(variables, ast.NameConstant(None))
                  self.statements.append(clear_format)
  
          else:  # Original assertion rewriting
              # Create failure message.
              body = self.expl_stmts
              self.statements.append(ast.If(negation, body, []))
              if assert_.msg:
                  assertmsg = self.helper("_format_assertmsg", assert_.msg)
                  explanation = "\n>assert " + explanation
              else:
                  assertmsg = ast.Str("")
                  explanation = "assert " + explanation
              template = ast.BinOp(assertmsg, ast.Add(), ast.Str(explanation))
              msg = self.pop_format_context(template)
              fmt = self.helper("_format_explanation", msg)
              err_name = ast.Name("AssertionError", ast.Load())
              exc = ast.Call(err_name, [fmt], [])
              raise_ = ast.Raise(exc, None)
  
              body.append(raise_)
  
          # Clear temporary variables by setting them to None.
          if self.variables:
              variables = [ast.Name(name, ast.Store()) for name in self.variables]
              clear = ast.Assign(variables, ast.NameConstant(None))
              self.statements.append(clear)
          # Fix line numbers.
          for stmt in self.statements:
              set_location(stmt, assert_.lineno, assert_.col_offset)
          return self.statements
  
      def visit_Name(self, name: ast.Name) -> Tuple[ast.Name, str]:
          # Display the repr of the name if it's a local variable or
          # _should_repr_global_name() thinks it's acceptable.
          locs = ast.Call(self.builtin("locals"), [], [])
          inlocs = ast.Compare(ast.Str(name.id), [ast.In()], [locs])
          dorepr = self.helper("_should_repr_global_name", name)
          test = ast.BoolOp(ast.Or(), [inlocs, dorepr])
          expr = ast.IfExp(test, self.display(name), ast.Str(name.id))
          return name, self.explanation_param(expr)
  
      def visit_BoolOp(self, boolop: ast.BoolOp) -> Tuple[ast.Name, str]:
          res_var = self.variable()
          expl_list = self.assign(ast.List([], ast.Load()))
          app = ast.Attribute(expl_list, "append", ast.Load())
          is_or = int(isinstance(boolop.op, ast.Or))
          body = save = self.statements
          fail_save = self.expl_stmts
          levels = len(boolop.values) - 1
          self.push_format_context()
          # Process each operand, short-circuiting if needed.
          for i, v in enumerate(boolop.values):
              if i:
                  fail_inner: List[ast.stmt] = []
                  # cond is set in a prior loop iteration below
                  self.expl_stmts.append(ast.If(cond, fail_inner, []))  # noqa
                  self.expl_stmts = fail_inner
              self.push_format_context()
              res, expl = self.visit(v)
              body.append(ast.Assign([ast.Name(res_var, ast.Store())], res))
              expl_format = self.pop_format_context(ast.Str(expl))
              call = ast.Call(app, [expl_format], [])
              self.expl_stmts.append(ast.Expr(call))
              if i < levels:
                  cond: ast.expr = res
                  if is_or:
                      cond = ast.UnaryOp(ast.Not(), cond)
                  inner: List[ast.stmt] = []
                  self.statements.append(ast.If(cond, inner, []))
                  self.statements = body = inner
          self.statements = save
          self.expl_stmts = fail_save
          expl_template = self.helper("_format_boolop", expl_list, ast.Num(is_or))
          expl = self.pop_format_context(expl_template)
          return ast.Name(res_var, ast.Load()), self.explanation_param(expl)
  
      def visit_UnaryOp(self, unary: ast.UnaryOp) -> Tuple[ast.Name, str]:
          pattern = UNARY_MAP[unary.op.__class__]
          operand_res, operand_expl = self.visit(unary.operand)
          res = self.assign(ast.UnaryOp(unary.op, operand_res))
          return res, pattern % (operand_expl,)
  
      def visit_BinOp(self, binop: ast.BinOp) -> Tuple[ast.Name, str]:
          symbol = BINOP_MAP[binop.op.__class__]
          left_expr, left_expl = self.visit(binop.left)
          right_expr, right_expl = self.visit(binop.right)
          explanation = f"({left_expl} {symbol} {right_expl})"
          res = self.assign(ast.BinOp(left_expr, binop.op, right_expr))
          return res, explanation
  
      def visit_Call(self, call: ast.Call) -> Tuple[ast.Name, str]:
          new_func, func_expl = self.visit(call.func)
          arg_expls = []
          new_args = []
          new_kwargs = []
          for arg in call.args:
              res, expl = self.visit(arg)
              arg_expls.append(expl)
              new_args.append(res)
          for keyword in call.keywords:
              res, expl = self.visit(keyword.value)
              new_kwargs.append(ast.keyword(keyword.arg, res))
              if keyword.arg:
                  arg_expls.append(keyword.arg + "=" + expl)
              else:  # **args have `arg` keywords with an .arg of None
                  arg_expls.append("**" + expl)
  
          expl = "{}({})".format(func_expl, ", ".join(arg_expls))
          new_call = ast.Call(new_func, new_args, new_kwargs)
          res = self.assign(new_call)
          res_expl = self.explanation_param(self.display(res))
          outer_expl = f"{res_expl}\n{{{res_expl} = {expl}\n}}"
          return res, outer_expl
  
      def visit_Starred(self, starred: ast.Starred) -> Tuple[ast.Starred, str]:
          # A Starred node can appear in a function call.
          res, expl = self.visit(starred.value)
          new_starred = ast.Starred(res, starred.ctx)
          return new_starred, "*" + expl
  
      def visit_Attribute(self, attr: ast.Attribute) -> Tuple[ast.Name, str]:
          if not isinstance(attr.ctx, ast.Load):
              return self.generic_visit(attr)
          value, value_expl = self.visit(attr.value)
          res = self.assign(ast.Attribute(value, attr.attr, ast.Load()))
          res_expl = self.explanation_param(self.display(res))
          pat = "%s\n{%s = %s.%s\n}"
          expl = pat % (res_expl, res_expl, value_expl, attr.attr)
          return res, expl
  
      def visit_Compare(self, comp: ast.Compare) -> Tuple[ast.expr, str]:
          self.push_format_context()
          left_res, left_expl = self.visit(comp.left)
          if isinstance(comp.left, (ast.Compare, ast.BoolOp)):
              left_expl = f"({left_expl})"
          res_variables = [self.variable() for i in range(len(comp.ops))]
          load_names = [ast.Name(v, ast.Load()) for v in res_variables]
          store_names = [ast.Name(v, ast.Store()) for v in res_variables]
          it = zip(range(len(comp.ops)), comp.ops, comp.comparators)
          expls = []
          syms = []
          results = [left_res]
          for i, op, next_operand in it:
              next_res, next_expl = self.visit(next_operand)
              if isinstance(next_operand, (ast.Compare, ast.BoolOp)):
                  next_expl = f"({next_expl})"
              results.append(next_res)
              sym = BINOP_MAP[op.__class__]
              syms.append(ast.Str(sym))
              expl = f"{left_expl} {sym} {next_expl}"
              expls.append(ast.Str(expl))
              res_expr = ast.Compare(left_res, [op], [next_res])
              self.statements.append(ast.Assign([store_names[i]], res_expr))
              left_res, left_expl = next_res, next_expl
          # Use pytest.assertion.util._reprcompare if that's available.
          expl_call = self.helper(
              "_call_reprcompare",
              ast.Tuple(syms, ast.Load()),
              ast.Tuple(load_names, ast.Load()),
              ast.Tuple(expls, ast.Load()),
              ast.Tuple(results, ast.Load()),
          )
          if len(comp.ops) > 1:
              res: ast.expr = ast.BoolOp(ast.And(), load_names)
          else:
              res = load_names[0]
          return res, self.explanation_param(self.pop_format_context(expl_call))
  
  
  def try_makedirs(cache_dir: Path) -> bool:
      """Attempt to create the given directory and sub-directories exist.
  
      Returns True if successful or if it already exists.
      """
      try:
          os.makedirs(os.fspath(cache_dir), exist_ok=True)
      except (FileNotFoundError, NotADirectoryError, FileExistsError):
          # One of the path components was not a directory:
          # - we're in a zip file
          # - it is a file
          return False
      except PermissionError:
          return False
      except OSError as e:
          # as of now, EROFS doesn't have an equivalent OSError-subclass
          if e.errno == errno.EROFS:
              return False
          raise
      return True
  
  
  def get_cache_dir(file_path: Path) -> Path:
      """Return the cache directory to write .pyc files for the given .py file path."""
      if sys.version_info >= (3, 8) and sys.pycache_prefix:
          # given:
          #   prefix = '/tmp/pycs'
          #   path = '/home/user/proj/test_app.py'
          # we want:
          #   '/tmp/pycs/home/user/proj'
          return Path(sys.pycache_prefix) / Path(*file_path.parts[1:-1])
      else:
          # classic pycache directory
          return file_path.parent / "__pycache__"
  