"""Per-test stdout/stderr capturing mechanism.""" import contextlib import functools import io import os import sys from io import UnsupportedOperation from tempfile import TemporaryFile from typing import Any from typing import AnyStr from typing import Generator from typing import Generic from typing import Iterator from typing import Optional from typing import TextIO from typing import Tuple from typing import TYPE_CHECKING from typing import Union from _pytest.compat import final from _pytest.config import Config from _pytest.config import hookimpl from _pytest.config.argparsing import Parser from _pytest.deprecated import check_ispytest from _pytest.fixtures import fixture from _pytest.fixtures import SubRequest from _pytest.nodes import Collector from _pytest.nodes import File from _pytest.nodes import Item if TYPE_CHECKING: from typing_extensions import Literal _CaptureMethod = Literal["fd", "sys", "no", "tee-sys"] def pytest_addoption(parser: Parser) -> None: group = parser.getgroup("general") group._addoption( "--capture", action="store", default="fd", metavar="method", choices=["fd", "sys", "no", "tee-sys"], help="per-test capturing method: one of fd|sys|no|tee-sys.", ) group._addoption( "-s", action="store_const", const="no", dest="capture", help="shortcut for --capture=no.", ) def _colorama_workaround() -> None: """Ensure colorama is imported so that it attaches to the correct stdio handles on Windows. colorama uses the terminal on import time. So if something does the first import of colorama while I/O capture is active, colorama will fail in various ways. """ if sys.platform.startswith("win32"): try: import colorama # noqa: F401 except ImportError: pass def _py36_windowsconsoleio_workaround(stream: TextIO) -> None: """Workaround for Windows Unicode console handling on Python>=3.6. Python 3.6 implemented Unicode console handling for Windows. This works by reading/writing to the raw console handle using ``{Read,Write}ConsoleW``. The problem is that we are going to ``dup2`` over the stdio file descriptors when doing ``FDCapture`` and this will ``CloseHandle`` the handles used by Python to write to the console. Though there is still some weirdness and the console handle seems to only be closed randomly and not on the first call to ``CloseHandle``, or maybe it gets reopened with the same handle value when we suspend capturing. The workaround in this case will reopen stdio with a different fd which also means a different handle by replicating the logic in "Py_lifecycle.c:initstdio/create_stdio". :param stream: In practice ``sys.stdout`` or ``sys.stderr``, but given here as parameter for unittesting purposes. See https://github.com/pytest-dev/py/issues/103. """ if not sys.platform.startswith("win32") or hasattr(sys, "pypy_version_info"): return # Bail out if ``stream`` doesn't seem like a proper ``io`` stream (#2666). if not hasattr(stream, "buffer"): # type: ignore[unreachable] return buffered = hasattr(stream.buffer, "raw") raw_stdout = stream.buffer.raw if buffered else stream.buffer # type: ignore[attr-defined] if not isinstance(raw_stdout, io._WindowsConsoleIO): # type: ignore[attr-defined] return def _reopen_stdio(f, mode): if not buffered and mode[0] == "w": buffering = 0 else: buffering = -1 return io.TextIOWrapper( open(os.dup(f.fileno()), mode, buffering), # type: ignore[arg-type] f.encoding, f.errors, f.newlines, f.line_buffering, ) sys.stdin = _reopen_stdio(sys.stdin, "rb") sys.stdout = _reopen_stdio(sys.stdout, "wb") sys.stderr = _reopen_stdio(sys.stderr, "wb") @hookimpl(hookwrapper=True) def pytest_load_initial_conftests(early_config: Config): ns = early_config.known_args_namespace if ns.capture == "fd": _py36_windowsconsoleio_workaround(sys.stdout) _colorama_workaround() pluginmanager = early_config.pluginmanager capman = CaptureManager(ns.capture) pluginmanager.register(capman, "capturemanager") # Make sure that capturemanager is properly reset at final shutdown. early_config.add_cleanup(capman.stop_global_capturing) # Finally trigger conftest loading but while capturing (issue #93). capman.start_global_capturing() outcome = yield capman.suspend_global_capture() if outcome.excinfo is not None: out, err = capman.read_global_capture() sys.stdout.write(out) sys.stderr.write(err) # IO Helpers. class EncodedFile(io.TextIOWrapper): __slots__ = () @property def name(self) -> str: # Ensure that file.name is a string. Workaround for a Python bug # fixed in >=3.7.4: https://bugs.python.org/issue36015 return repr(self.buffer) @property def mode(self) -> str: # TextIOWrapper doesn't expose a mode, but at least some of our # tests check it. return self.buffer.mode.replace("b", "") class CaptureIO(io.TextIOWrapper): def __init__(self) -> None: super().__init__(io.BytesIO(), encoding="UTF-8", newline="", write_through=True) def getvalue(self) -> str: assert isinstance(self.buffer, io.BytesIO) return self.buffer.getvalue().decode("UTF-8") class TeeCaptureIO(CaptureIO): def __init__(self, other: TextIO) -> None: self._other = other super().__init__() def write(self, s: str) -> int: super().write(s) return self._other.write(s) class DontReadFromInput: encoding = None def read(self, *args): raise OSError( "pytest: reading from stdin while output is captured! Consider using `-s`." ) readline = read readlines = read __next__ = read def __iter__(self): return self def fileno(self) -> int: raise UnsupportedOperation("redirected stdin is pseudofile, has no fileno()") def isatty(self) -> bool: return False def close(self) -> None: pass @property def buffer(self): return self # Capture classes. patchsysdict = {0: "stdin", 1: "stdout", 2: "stderr"} class NoCapture: EMPTY_BUFFER = None __init__ = start = done = suspend = resume = lambda *args: None class SysCaptureBinary: EMPTY_BUFFER = b"" def __init__(self, fd: int, tmpfile=None, *, tee: bool = False) -> None: name = patchsysdict[fd] self._old = getattr(sys, name) self.name = name if tmpfile is None: if name == "stdin": tmpfile = DontReadFromInput() else: tmpfile = CaptureIO() if not tee else TeeCaptureIO(self._old) self.tmpfile = tmpfile self._state = "initialized" def repr(self, class_name: str) -> str: return "<{} {} _old={} _state={!r} tmpfile={!r}>".format( class_name, self.name, hasattr(self, "_old") and repr(self._old) or "", self._state, self.tmpfile, ) def __repr__(self) -> str: return "<{} {} _old={} _state={!r} tmpfile={!r}>".format( self.__class__.__name__, self.name, hasattr(self, "_old") and repr(self._old) or "", self._state, self.tmpfile, ) def _assert_state(self, op: str, states: Tuple[str, ...]) -> None: assert ( self._state in states ), "cannot {} in state {!r}: expected one of {}".format( op, self._state, ", ".join(states) ) def start(self) -> None: self._assert_state("start", ("initialized",)) setattr(sys, self.name, self.tmpfile) self._state = "started" def snap(self): self._assert_state("snap", ("started", "suspended")) self.tmpfile.seek(0) res = self.tmpfile.buffer.read() self.tmpfile.seek(0) self.tmpfile.truncate() return res def done(self) -> None: self._assert_state("done", ("initialized", "started", "suspended", "done")) if self._state == "done": return setattr(sys, self.name, self._old) del self._old self.tmpfile.close() self._state = "done" def suspend(self) -> None: self._assert_state("suspend", ("started", "suspended")) setattr(sys, self.name, self._old) self._state = "suspended" def resume(self) -> None: self._assert_state("resume", ("started", "suspended")) if self._state == "started": return setattr(sys, self.name, self.tmpfile) self._state = "started" def writeorg(self, data) -> None: self._assert_state("writeorg", ("started", "suspended")) self._old.flush() self._old.buffer.write(data) self._old.buffer.flush() class SysCapture(SysCaptureBinary): EMPTY_BUFFER = "" # type: ignore[assignment] def snap(self): res = self.tmpfile.getvalue() self.tmpfile.seek(0) self.tmpfile.truncate() return res def writeorg(self, data): self._assert_state("writeorg", ("started", "suspended")) self._old.write(data) self._old.flush() class FDCaptureBinary: """Capture IO to/from a given OS-level file descriptor. snap() produces `bytes`. """ EMPTY_BUFFER = b"" def __init__(self, targetfd: int) -> None: self.targetfd = targetfd try: os.fstat(targetfd) except OSError: # FD capturing is conceptually simple -- create a temporary file, # redirect the FD to it, redirect back when done. But when the # target FD is invalid it throws a wrench into this lovely scheme. # # Tests themselves shouldn't care if the FD is valid, FD capturing # should work regardless of external circumstances. So falling back # to just sys capturing is not a good option. # # Further complications are the need to support suspend() and the # possibility of FD reuse (e.g. the tmpfile getting the very same # target FD). The following approach is robust, I believe. self.targetfd_invalid: Optional[int] = os.open(os.devnull, os.O_RDWR) os.dup2(self.targetfd_invalid, targetfd) else: self.targetfd_invalid = None self.targetfd_save = os.dup(targetfd) if targetfd == 0: self.tmpfile = open(os.devnull) self.syscapture = SysCapture(targetfd) else: self.tmpfile = EncodedFile( TemporaryFile(buffering=0), encoding="utf-8", errors="replace", newline="", write_through=True, ) if targetfd in patchsysdict: self.syscapture = SysCapture(targetfd, self.tmpfile) else: self.syscapture = NoCapture() self._state = "initialized" def __repr__(self) -> str: return "<{} {} oldfd={} _state={!r} tmpfile={!r}>".format( self.__class__.__name__, self.targetfd, self.targetfd_save, self._state, self.tmpfile, ) def _assert_state(self, op: str, states: Tuple[str, ...]) -> None: assert ( self._state in states ), "cannot {} in state {!r}: expected one of {}".format( op, self._state, ", ".join(states) ) def start(self) -> None: """Start capturing on targetfd using memorized tmpfile.""" self._assert_state("start", ("initialized",)) os.dup2(self.tmpfile.fileno(), self.targetfd) self.syscapture.start() self._state = "started" def snap(self): self._assert_state("snap", ("started", "suspended")) self.tmpfile.seek(0) res = self.tmpfile.buffer.read() self.tmpfile.seek(0) self.tmpfile.truncate() return res def done(self) -> None: """Stop capturing, restore streams, return original capture file, seeked to position zero.""" self._assert_state("done", ("initialized", "started", "suspended", "done")) if self._state == "done": return os.dup2(self.targetfd_save, self.targetfd) os.close(self.targetfd_save) if self.targetfd_invalid is not None: if self.targetfd_invalid != self.targetfd: os.close(self.targetfd) os.close(self.targetfd_invalid) self.syscapture.done() self.tmpfile.close() self._state = "done" def suspend(self) -> None: self._assert_state("suspend", ("started", "suspended")) if self._state == "suspended": return self.syscapture.suspend() os.dup2(self.targetfd_save, self.targetfd) self._state = "suspended" def resume(self) -> None: self._assert_state("resume", ("started", "suspended")) if self._state == "started": return self.syscapture.resume() os.dup2(self.tmpfile.fileno(), self.targetfd) self._state = "started" def writeorg(self, data): """Write to original file descriptor.""" self._assert_state("writeorg", ("started", "suspended")) os.write(self.targetfd_save, data) class FDCapture(FDCaptureBinary): """Capture IO to/from a given OS-level file descriptor. snap() produces text. """ # Ignore type because it doesn't match the type in the superclass (bytes). EMPTY_BUFFER = "" # type: ignore def snap(self): self._assert_state("snap", ("started", "suspended")) self.tmpfile.seek(0) res = self.tmpfile.read() self.tmpfile.seek(0) self.tmpfile.truncate() return res def writeorg(self, data): """Write to original file descriptor.""" super().writeorg(data.encode("utf-8")) # XXX use encoding of original stream # MultiCapture # This class was a namedtuple, but due to mypy limitation[0] it could not be # made generic, so was replaced by a regular class which tries to emulate the # pertinent parts of a namedtuple. If the mypy limitation is ever lifted, can # make it a namedtuple again. # [0]: https://github.com/python/mypy/issues/685 @final @functools.total_ordering class CaptureResult(Generic[AnyStr]): """The result of :method:`CaptureFixture.readouterr`.""" __slots__ = ("out", "err") def __init__(self, out: AnyStr, err: AnyStr) -> None: self.out: AnyStr = out self.err: AnyStr = err def __len__(self) -> int: return 2 def __iter__(self) -> Iterator[AnyStr]: return iter((self.out, self.err)) def __getitem__(self, item: int) -> AnyStr: return tuple(self)[item] def _replace( self, *, out: Optional[AnyStr] = None, err: Optional[AnyStr] = None ) -> "CaptureResult[AnyStr]": return CaptureResult( out=self.out if out is None else out, err=self.err if err is None else err ) def count(self, value: AnyStr) -> int: return tuple(self).count(value) def index(self, value) -> int: return tuple(self).index(value) def __eq__(self, other: object) -> bool: if not isinstance(other, (CaptureResult, tuple)): return NotImplemented return tuple(self) == tuple(other) def __hash__(self) -> int: return hash(tuple(self)) def __lt__(self, other: object) -> bool: if not isinstance(other, (CaptureResult, tuple)): return NotImplemented return tuple(self) < tuple(other) def __repr__(self) -> str: return f"CaptureResult(out={self.out!r}, err={self.err!r})" class MultiCapture(Generic[AnyStr]): _state = None _in_suspended = False def __init__(self, in_, out, err) -> None: self.in_ = in_ self.out = out self.err = err def __repr__(self) -> str: return "".format( self.out, self.err, self.in_, self._state, self._in_suspended, ) def start_capturing(self) -> None: self._state = "started" if self.in_: self.in_.start() if self.out: self.out.start() if self.err: self.err.start() def pop_outerr_to_orig(self) -> Tuple[AnyStr, AnyStr]: """Pop current snapshot out/err capture and flush to orig streams.""" out, err = self.readouterr() if out: self.out.writeorg(out) if err: self.err.writeorg(err) return out, err def suspend_capturing(self, in_: bool = False) -> None: self._state = "suspended" if self.out: self.out.suspend() if self.err: self.err.suspend() if in_ and self.in_: self.in_.suspend() self._in_suspended = True def resume_capturing(self) -> None: self._state = "started" if self.out: self.out.resume() if self.err: self.err.resume() if self._in_suspended: self.in_.resume() self._in_suspended = False def stop_capturing(self) -> None: """Stop capturing and reset capturing streams.""" if self._state == "stopped": raise ValueError("was already stopped") self._state = "stopped" if self.out: self.out.done() if self.err: self.err.done() if self.in_: self.in_.done() def is_started(self) -> bool: """Whether actively capturing -- not suspended or stopped.""" return self._state == "started" def readouterr(self) -> CaptureResult[AnyStr]: out = self.out.snap() if self.out else "" err = self.err.snap() if self.err else "" return CaptureResult(out, err) def _get_multicapture(method: "_CaptureMethod") -> MultiCapture[str]: if method == "fd": return MultiCapture(in_=FDCapture(0), out=FDCapture(1), err=FDCapture(2)) elif method == "sys": return MultiCapture(in_=SysCapture(0), out=SysCapture(1), err=SysCapture(2)) elif method == "no": return MultiCapture(in_=None, out=None, err=None) elif method == "tee-sys": return MultiCapture( in_=None, out=SysCapture(1, tee=True), err=SysCapture(2, tee=True) ) raise ValueError(f"unknown capturing method: {method!r}") # CaptureManager and CaptureFixture class CaptureManager: """The capture plugin. Manages that the appropriate capture method is enabled/disabled during collection and each test phase (setup, call, teardown). After each of those points, the captured output is obtained and attached to the collection/runtest report. There are two levels of capture: * global: enabled by default and can be suppressed by the ``-s`` option. This is always enabled/disabled during collection and each test phase. * fixture: when a test function or one of its fixture depend on the ``capsys`` or ``capfd`` fixtures. In this case special handling is needed to ensure the fixtures take precedence over the global capture. """ def __init__(self, method: "_CaptureMethod") -> None: self._method = method self._global_capturing: Optional[MultiCapture[str]] = None self._capture_fixture: Optional[CaptureFixture[Any]] = None def __repr__(self) -> str: return "".format( self._method, self._global_capturing, self._capture_fixture ) def is_capturing(self) -> Union[str, bool]: if self.is_globally_capturing(): return "global" if self._capture_fixture: return "fixture %s" % self._capture_fixture.request.fixturename return False # Global capturing control def is_globally_capturing(self) -> bool: return self._method != "no" def start_global_capturing(self) -> None: assert self._global_capturing is None self._global_capturing = _get_multicapture(self._method) self._global_capturing.start_capturing() def stop_global_capturing(self) -> None: if self._global_capturing is not None: self._global_capturing.pop_outerr_to_orig() self._global_capturing.stop_capturing() self._global_capturing = None def resume_global_capture(self) -> None: # During teardown of the python process, and on rare occasions, capture # attributes can be `None` while trying to resume global capture. if self._global_capturing is not None: self._global_capturing.resume_capturing() def suspend_global_capture(self, in_: bool = False) -> None: if self._global_capturing is not None: self._global_capturing.suspend_capturing(in_=in_) def suspend(self, in_: bool = False) -> None: # Need to undo local capsys-et-al if it exists before disabling global capture. self.suspend_fixture() self.suspend_global_capture(in_) def resume(self) -> None: self.resume_global_capture() self.resume_fixture() def read_global_capture(self) -> CaptureResult[str]: assert self._global_capturing is not None return self._global_capturing.readouterr() # Fixture Control def set_fixture(self, capture_fixture: "CaptureFixture[Any]") -> None: if self._capture_fixture: current_fixture = self._capture_fixture.request.fixturename requested_fixture = capture_fixture.request.fixturename capture_fixture.request.raiseerror( "cannot use {} and {} at the same time".format( requested_fixture, current_fixture ) ) self._capture_fixture = capture_fixture def unset_fixture(self) -> None: self._capture_fixture = None def activate_fixture(self) -> None: """If the current item is using ``capsys`` or ``capfd``, activate them so they take precedence over the global capture.""" if self._capture_fixture: self._capture_fixture._start() def deactivate_fixture(self) -> None: """Deactivate the ``capsys`` or ``capfd`` fixture of this item, if any.""" if self._capture_fixture: self._capture_fixture.close() def suspend_fixture(self) -> None: if self._capture_fixture: self._capture_fixture._suspend() def resume_fixture(self) -> None: if self._capture_fixture: self._capture_fixture._resume() # Helper context managers @contextlib.contextmanager def global_and_fixture_disabled(self) -> Generator[None, None, None]: """Context manager to temporarily disable global and current fixture capturing.""" do_fixture = self._capture_fixture and self._capture_fixture._is_started() if do_fixture: self.suspend_fixture() do_global = self._global_capturing and self._global_capturing.is_started() if do_global: self.suspend_global_capture() try: yield finally: if do_global: self.resume_global_capture() if do_fixture: self.resume_fixture() @contextlib.contextmanager def item_capture(self, when: str, item: Item) -> Generator[None, None, None]: self.resume_global_capture() self.activate_fixture() try: yield finally: self.deactivate_fixture() self.suspend_global_capture(in_=False) out, err = self.read_global_capture() item.add_report_section(when, "stdout", out) item.add_report_section(when, "stderr", err) # Hooks @hookimpl(hookwrapper=True) def pytest_make_collect_report(self, collector: Collector): if isinstance(collector, File): self.resume_global_capture() outcome = yield self.suspend_global_capture() out, err = self.read_global_capture() rep = outcome.get_result() if out: rep.sections.append(("Captured stdout", out)) if err: rep.sections.append(("Captured stderr", err)) else: yield @hookimpl(hookwrapper=True) def pytest_runtest_setup(self, item: Item) -> Generator[None, None, None]: with self.item_capture("setup", item): yield @hookimpl(hookwrapper=True) def pytest_runtest_call(self, item: Item) -> Generator[None, None, None]: with self.item_capture("call", item): yield @hookimpl(hookwrapper=True) def pytest_runtest_teardown(self, item: Item) -> Generator[None, None, None]: with self.item_capture("teardown", item): yield @hookimpl(tryfirst=True) def pytest_keyboard_interrupt(self) -> None: self.stop_global_capturing() @hookimpl(tryfirst=True) def pytest_internalerror(self) -> None: self.stop_global_capturing() class CaptureFixture(Generic[AnyStr]): """Object returned by the :fixture:`capsys`, :fixture:`capsysbinary`, :fixture:`capfd` and :fixture:`capfdbinary` fixtures.""" def __init__( self, captureclass, request: SubRequest, *, _ispytest: bool = False ) -> None: check_ispytest(_ispytest) self.captureclass = captureclass self.request = request self._capture: Optional[MultiCapture[AnyStr]] = None self._captured_out = self.captureclass.EMPTY_BUFFER self._captured_err = self.captureclass.EMPTY_BUFFER def _start(self) -> None: if self._capture is None: self._capture = MultiCapture( in_=None, out=self.captureclass(1), err=self.captureclass(2), ) self._capture.start_capturing() def close(self) -> None: if self._capture is not None: out, err = self._capture.pop_outerr_to_orig() self._captured_out += out self._captured_err += err self._capture.stop_capturing() self._capture = None def readouterr(self) -> CaptureResult[AnyStr]: """Read and return the captured output so far, resetting the internal buffer. :returns: The captured content as a namedtuple with ``out`` and ``err`` string attributes. """ captured_out, captured_err = self._captured_out, self._captured_err if self._capture is not None: out, err = self._capture.readouterr() captured_out += out captured_err += err self._captured_out = self.captureclass.EMPTY_BUFFER self._captured_err = self.captureclass.EMPTY_BUFFER return CaptureResult(captured_out, captured_err) def _suspend(self) -> None: """Suspend this fixture's own capturing temporarily.""" if self._capture is not None: self._capture.suspend_capturing() def _resume(self) -> None: """Resume this fixture's own capturing temporarily.""" if self._capture is not None: self._capture.resume_capturing() def _is_started(self) -> bool: """Whether actively capturing -- not disabled or closed.""" if self._capture is not None: return self._capture.is_started() return False @contextlib.contextmanager def disabled(self) -> Generator[None, None, None]: """Temporarily disable capturing while inside the ``with`` block.""" capmanager = self.request.config.pluginmanager.getplugin("capturemanager") with capmanager.global_and_fixture_disabled(): yield # The fixtures. @fixture def capsys(request: SubRequest) -> Generator[CaptureFixture[str], None, None]: """Enable text capturing of writes to ``sys.stdout`` and ``sys.stderr``. The captured output is made available via ``capsys.readouterr()`` method calls, which return a ``(out, err)`` namedtuple. ``out`` and ``err`` will be ``text`` objects. """ capman = request.config.pluginmanager.getplugin("capturemanager") capture_fixture = CaptureFixture[str](SysCapture, request, _ispytest=True) capman.set_fixture(capture_fixture) capture_fixture._start() yield capture_fixture capture_fixture.close() capman.unset_fixture() @fixture def capsysbinary(request: SubRequest) -> Generator[CaptureFixture[bytes], None, None]: """Enable bytes capturing of writes to ``sys.stdout`` and ``sys.stderr``. The captured output is made available via ``capsysbinary.readouterr()`` method calls, which return a ``(out, err)`` namedtuple. ``out`` and ``err`` will be ``bytes`` objects. """ capman = request.config.pluginmanager.getplugin("capturemanager") capture_fixture = CaptureFixture[bytes](SysCaptureBinary, request, _ispytest=True) capman.set_fixture(capture_fixture) capture_fixture._start() yield capture_fixture capture_fixture.close() capman.unset_fixture() @fixture def capfd(request: SubRequest) -> Generator[CaptureFixture[str], None, None]: """Enable text capturing of writes to file descriptors ``1`` and ``2``. The captured output is made available via ``capfd.readouterr()`` method calls, which return a ``(out, err)`` namedtuple. ``out`` and ``err`` will be ``text`` objects. """ capman = request.config.pluginmanager.getplugin("capturemanager") capture_fixture = CaptureFixture[str](FDCapture, request, _ispytest=True) capman.set_fixture(capture_fixture) capture_fixture._start() yield capture_fixture capture_fixture.close() capman.unset_fixture() @fixture def capfdbinary(request: SubRequest) -> Generator[CaptureFixture[bytes], None, None]: """Enable bytes capturing of writes to file descriptors ``1`` and ``2``. The captured output is made available via ``capfd.readouterr()`` method calls, which return a ``(out, err)`` namedtuple. ``out`` and ``err`` will be ``byte`` objects. """ capman = request.config.pluginmanager.getplugin("capturemanager") capture_fixture = CaptureFixture[bytes](FDCaptureBinary, request, _ispytest=True) capman.set_fixture(capture_fixture) capture_fixture._start() yield capture_fixture capture_fixture.close() capman.unset_fixture()