← Back
Editing: rewrite.py
"""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 Iterator 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 if sys.version_info >= (3, 8): namedExpr = ast.NamedExpr astNameConstant = ast.Constant astStr = ast.Constant astNum = ast.Constant else: namedExpr = ast.Expr astNameConstant = ast.NameConstant astStr = ast.Str astNum = ast.Num 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: Dict[str, Path] = {} 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 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[module.__name__] = fn # 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.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(*parts).with_suffix(".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() if sys.version_info >= (3, 10): if sys.version_info >= (3, 12): from importlib.resources.abc import TraversableResources else: from importlib.abc import TraversableResources def get_resource_reader(self, name: str) -> TraversableResources: # type: ignore if sys.version_info < (3, 11): from importlib.readers import FileReader else: from importlib.resources.readers import FileReader return FileReader( # type:ignore[no-any-return] types.SimpleNamespace(path=self._rewritten_names[name]) ) 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/ 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)) def _write_pyc( state: "AssertionState", co: types.CodeType, source_stat: os.stat_result, pyc: Path, ) -> bool: proc_pyc = f"{pyc}.{os.getpid()}" try: with open(proc_pyc, "wb") as fp: _write_pyc_fp(fp, source_stat, co) except OSError as e: state.trace(f"error writing pyc file at {proc_pyc}: errno={e.errno}") return False try: os.replace(proc_pyc, 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 return True def _rewrite_test(fn: Path, config: Config) -> Tuple[os.stat_result, types.CodeType]: """Read and rewrite *fn* and return the code object.""" stat = os.stat(fn) source = fn.read_bytes() strfn = str(fn) tree = ast.parse(source, filename=strfn) rewrite_asserts(tree, source, strfn, config) co = compile(tree, strfn, "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(pyc, "rb") except OSError: return None with fp: try: stat_result = os.stat(source) mtime = int(stat_result.st_mtime) size = stat_result.st_size data = fp.read(16) 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): 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 data[4:8] != b"\x00\x00\x00\x00": trace("_read_pyc(%s): invalid pyc (unsupported flags)" % source) return None mtime_data = data[8:12] if int.from_bytes(mtime_data, "little") != mtime & 0xFFFFFFFF: trace("_read_pyc(%s): out of date" % source) return None size_data = data[12:16] 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 unnecessarily (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 traverse_node(node: ast.AST) -> Iterator[ast.AST]: """Recursively yield node and all its children in depth-first order.""" yield node for child in ast.iter_child_nodes(node): yield from traverse_node(child) @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. :variables_overwrite: A dict filled with references to variables that change value within an assert. This happens when a variable is reassigned with the walrus operator This state, except the variables_overwrite, 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 self.variables_overwrite: Dict[str, str] = {} 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 item = None for item in mod.body: if ( expect_docstring and isinstance(item, ast.Expr) and isinstance(item.value, astStr) ): if sys.version_info >= (3, 8): doc = item.value.value else: 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 = [astStr(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=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(astStr(explanation)) # Failed if assert_.msg: assertmsg = self.helper("_format_assertmsg", assert_.msg) gluestr = "\n>assert " else: assertmsg = astStr("") gluestr = "assert " err_explanation = ast.BinOp(astStr(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", astNum(assert_.lineno), astStr(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, astNameConstant(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 = astStr("") explanation = "assert " + explanation template = ast.BinOp(assertmsg, ast.Add(), astStr(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, astNameConstant(None)) self.statements.append(clear) # Fix locations (line numbers/column offsets). for stmt in self.statements: for node in traverse_node(stmt): ast.copy_location(node, assert_) return self.statements def visit_NamedExpr(self, name: namedExpr) -> Tuple[namedExpr, str]: # This method handles the 'walrus operator' repr of the target # name if it's a local variable or _should_repr_global_name() # thinks it's acceptable. locs = ast.Call(self.builtin("locals"), [], []) target_id = name.target.id # type: ignore[attr-defined] inlocs = ast.Compare(astStr(target_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), astStr(target_id)) return name, self.explanation_param(expr) 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(astStr(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), astStr(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 # Check if the left operand is a namedExpr and the value has already been visited if ( isinstance(v, ast.Compare) and isinstance(v.left, namedExpr) and v.left.target.id in [ ast_expr.id for ast_expr in boolop.values[:i] if hasattr(ast_expr, "id") ] ): pytest_temp = self.variable() self.variables_overwrite[ v.left.target.id ] = v.left # type:ignore[assignment] v.left.target.id = pytest_temp 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(astStr(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, astNum(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: if isinstance(arg, ast.Name) and arg.id in self.variables_overwrite: arg = self.variables_overwrite[arg.id] # type:ignore[assignment] res, expl = self.visit(arg) arg_expls.append(expl) new_args.append(res) for keyword in call.keywords: if ( isinstance(keyword.value, ast.Name) and keyword.value.id in self.variables_overwrite ): keyword.value = self.variables_overwrite[ keyword.value.id ] # type:ignore[assignment] 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() # We first check if we have overwritten a variable in the previous assert if isinstance(comp.left, ast.Name) and comp.left.id in self.variables_overwrite: comp.left = self.variables_overwrite[ comp.left.id ] # type:ignore[assignment] if isinstance(comp.left, namedExpr): self.variables_overwrite[ comp.left.target.id ] = comp.left # type:ignore[assignment] 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: if ( isinstance(next_operand, namedExpr) and isinstance(left_res, ast.Name) and next_operand.target.id == left_res.id ): next_operand.target.id = self.variable() self.variables_overwrite[ left_res.id ] = next_operand # type:ignore[assignment] 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(astStr(sym)) expl = f"{left_expl} {sym} {next_expl}" expls.append(astStr(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(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__"
Save File
Cancel