"""
per-test stdout/stderr capturing mechanism.
"""
import collections
import contextlib
import enum
import io
import os
import sys
from io import UnsupportedOperation
from tempfile import TemporaryFile
from typing import BinaryIO
from typing import Generator
from typing import Iterable
from typing import Optional
import pytest
from _pytest.compat import CaptureAndPassthroughIO
from _pytest.compat import CaptureIO
from _pytest.compat import TYPE_CHECKING
from _pytest.config import Config
from _pytest.fixtures import FixtureRequest
if TYPE_CHECKING:
from typing_extensions import Literal
_CaptureMethod = Literal["fd", "sys", "no", "tee-sys"]
patchsysdict = {0: "stdin", 1: "stdout", 2: "stderr"}
class CloseStdinType(enum.Enum):
CLOSE_STDIN = 1
CLOSE_STDIN = CloseStdinType.CLOSE_STDIN
"""Sentinel to close stdin."""
def pytest_addoption(parser):
group = parser.getgroup("general")
group._addoption(
"--capture",
action="store",
default="fd" if hasattr(os, "dup") else "sys",
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.",
)
@pytest.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()
_readline_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 (issue93)
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)
def _get_multicapture(method: "_CaptureMethod") -> "MultiCapture":
if method == "fd":
return MultiCapture(out=True, err=True, Capture=FDCapture)
elif method == "sys":
return MultiCapture(out=True, err=True, Capture=SysCapture)
elif method == "no":
return MultiCapture(out=False, err=False, in_=False)
elif method == "tee-sys":
return MultiCapture(out=True, err=True, in_=False, Capture=TeeSysCapture)
raise ValueError("unknown capturing method: {!r}".format(method))
class CaptureManager:
"""
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: which is 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 = None
self._capture_fixture = None # type: Optional[CaptureFixture]
def __repr__(self):
return "<CaptureManager _method={!r} _global_capturing={!r} _capture_fixture={!r}>".format(
self._method, self._global_capturing, self._capture_fixture
)
def is_capturing(self):
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):
return self._method != "no"
def start_global_capturing(self):
assert self._global_capturing is None
self._global_capturing = _get_multicapture(self._method)
self._global_capturing.start_capturing()
def stop_global_capturing(self):
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):
# 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_=False):
cap = getattr(self, "_global_capturing", None)
if cap is not None:
cap.suspend_capturing(in_=in_)
def suspend(self, in_=False):
# 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):
self.resume_global_capture()
self.resume_fixture()
def read_global_capture(self):
return self._global_capturing.readouterr()
# Fixture Control (it's just forwarding, think about removing this later)
@contextlib.contextmanager
def _capturing_for_request(
self, request: FixtureRequest
) -> Generator["CaptureFixture", None, None]:
"""
Context manager that creates a ``CaptureFixture`` instance for the
given ``request``, ensuring there is only a single one being requested
at the same time.
This is used as a helper with ``capsys``, ``capfd`` etc.
"""
if self._capture_fixture:
other_name = next(
k
for k, v in map_fixname_class.items()
if v is self._capture_fixture.captureclass
)
raise request.raiseerror(
"cannot use {} and {} at the same time".format(
request.fixturename, other_name
)
)
capture_class = map_fixname_class[request.fixturename]
self._capture_fixture = CaptureFixture(capture_class, request)
self.activate_fixture()
yield self._capture_fixture
self._capture_fixture.close()
self._capture_fixture = None
def activate_fixture(self):
"""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):
"""Deactivates the ``capsys`` or ``capfd`` fixture of this item, if any."""
if self._capture_fixture:
self._capture_fixture.close()
def suspend_fixture(self):
if self._capture_fixture:
self._capture_fixture._suspend()
def resume_fixture(self):
if self._capture_fixture:
self._capture_fixture._resume()
# Helper context managers
@contextlib.contextmanager
def global_and_fixture_disabled(self):
"""Context manager to temporarily disable global and current fixture capturing."""
self.suspend()
try:
yield
finally:
self.resume()
@contextlib.contextmanager
def item_capture(self, when, item):
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
@pytest.hookimpl(hookwrapper=True)
def pytest_make_collect_report(self, collector):
if isinstance(collector, pytest.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
@pytest.hookimpl(hookwrapper=True)
def pytest_runtest_setup(self, item):
with self.item_capture("setup", item):
yield
@pytest.hookimpl(hookwrapper=True)
def pytest_runtest_call(self, item):
with self.item_capture("call", item):
yield
@pytest.hookimpl(hookwrapper=True)
def pytest_runtest_teardown(self, item):
with self.item_capture("teardown", item):
yield
@pytest.hookimpl(tryfirst=True)
def pytest_keyboard_interrupt(self, excinfo):
self.stop_global_capturing()
@pytest.hookimpl(tryfirst=True)
def pytest_internalerror(self, excinfo):
self.stop_global_capturing()
[docs]@pytest.fixture
def capsys(request):
"""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")
with capman._capturing_for_request(request) as fixture:
yield fixture
[docs]@pytest.fixture
def capsysbinary(request):
"""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")
with capman._capturing_for_request(request) as fixture:
yield fixture
[docs]@pytest.fixture
def capfd(request):
"""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.
"""
if not hasattr(os, "dup"):
pytest.skip(
"capfd fixture needs os.dup function which is not available in this system"
)
capman = request.config.pluginmanager.getplugin("capturemanager")
with capman._capturing_for_request(request) as fixture:
yield fixture
[docs]@pytest.fixture
def capfdbinary(request):
"""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.
"""
if not hasattr(os, "dup"):
pytest.skip(
"capfdbinary fixture needs os.dup function which is not available in this system"
)
capman = request.config.pluginmanager.getplugin("capturemanager")
with capman._capturing_for_request(request) as fixture:
yield fixture
[docs]class CaptureFixture:
"""
Object returned by :py:func:`capsys`, :py:func:`capsysbinary`, :py:func:`capfd` and :py:func:`capfdbinary`
fixtures.
"""
def __init__(self, captureclass, request):
self.captureclass = captureclass
self.request = request
self._capture = None
self._captured_out = self.captureclass.EMPTY_BUFFER
self._captured_err = self.captureclass.EMPTY_BUFFER
def _start(self):
if self._capture is None:
self._capture = MultiCapture(
out=True, err=True, in_=False, Capture=self.captureclass
)
self._capture.start_capturing()
def close(self):
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
[docs] def readouterr(self):
"""Read and return the captured output so far, resetting the internal buffer.
:return: 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):
"""Suspends this fixture's own capturing temporarily."""
if self._capture is not None:
self._capture.suspend_capturing()
def _resume(self):
"""Resumes this fixture's own capturing temporarily."""
if self._capture is not None:
self._capture.resume_capturing()
[docs] @contextlib.contextmanager
def disabled(self):
"""Temporarily disables capture while inside the 'with' block."""
capmanager = self.request.config.pluginmanager.getplugin("capturemanager")
with capmanager.global_and_fixture_disabled():
yield
def safe_text_dupfile(f, mode, default_encoding="UTF8"):
""" return an open text file object that's a duplicate of f on the
FD-level if possible.
"""
encoding = getattr(f, "encoding", None)
try:
fd = f.fileno()
except Exception:
if "b" not in getattr(f, "mode", "") and hasattr(f, "encoding"):
# we seem to have a text stream, let's just use it
return f
else:
newfd = os.dup(fd)
if "b" not in mode:
mode += "b"
f = os.fdopen(newfd, mode, 0) # no buffering
return EncodedFile(f, encoding or default_encoding)
class EncodedFile:
errors = "strict" # possibly needed by py3 code (issue555)
def __init__(self, buffer: BinaryIO, encoding: str) -> None:
self.buffer = buffer
self.encoding = encoding
def write(self, s: str) -> int:
if not isinstance(s, str):
raise TypeError(
"write() argument must be str, not {}".format(type(s).__name__)
)
return self.buffer.write(s.encode(self.encoding, "replace"))
def writelines(self, lines: Iterable[str]) -> None:
self.buffer.writelines(x.encode(self.encoding, "replace") for x in lines)
@property
def name(self) -> str:
"""Ensure that file.name is a string."""
return repr(self.buffer)
@property
def mode(self) -> str:
return self.buffer.mode.replace("b", "")
def __getattr__(self, name):
return getattr(object.__getattribute__(self, "buffer"), name)
CaptureResult = collections.namedtuple("CaptureResult", ["out", "err"])
class MultiCapture:
out = err = in_ = None
_state = None
_in_suspended = False
def __init__(self, out=True, err=True, in_=True, Capture=None):
if in_:
self.in_ = Capture(0)
if out:
self.out = Capture(1)
if err:
self.err = Capture(2)
def __repr__(self):
return "<MultiCapture out={!r} err={!r} in_={!r} _state={!r} _in_suspended={!r}>".format(
self.out, self.err, self.in_, self._state, self._in_suspended,
)
def start_capturing(self):
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):
""" 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_=False):
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):
self._state = "resumed"
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):
""" 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 readouterr(self):
""" return snapshot unicode value of stdout/stderr capturings. """
return CaptureResult(
self.out.snap() if self.out is not None else "",
self.err.snap() if self.err is not None else "",
)
class NoCapture:
EMPTY_BUFFER = None
__init__ = start = done = suspend = resume = lambda *args: None
class FDCaptureBinary:
"""Capture IO to/from a given os-level filedescriptor.
snap() produces `bytes`
"""
EMPTY_BUFFER = b""
_state = None
def __init__(self, targetfd, tmpfile=None):
self.targetfd = targetfd
try:
self.targetfd_save = os.dup(self.targetfd)
except OSError:
self.start = lambda: None
self.done = lambda: None
else:
self.start = self._start
self.done = self._done
if targetfd == 0:
assert not tmpfile, "cannot set tmpfile with stdin"
tmpfile = open(os.devnull, "r")
self.syscapture = SysCapture(targetfd)
else:
if tmpfile is None:
f = TemporaryFile()
with f:
tmpfile = safe_text_dupfile(f, mode="wb+")
if targetfd in patchsysdict:
self.syscapture = SysCapture(targetfd, tmpfile)
else:
self.syscapture = NoCapture()
self.tmpfile = tmpfile
self.tmpfile_fd = tmpfile.fileno()
def __repr__(self):
return "<{} {} oldfd={} _state={!r} tmpfile={}>".format(
self.__class__.__name__,
self.targetfd,
getattr(self, "targetfd_save", "<UNSET>"),
self._state,
hasattr(self, "tmpfile") and repr(self.tmpfile) or "<UNSET>",
)
def _start(self):
""" Start capturing on targetfd using memorized tmpfile. """
try:
os.fstat(self.targetfd_save)
except (AttributeError, OSError):
raise ValueError("saved filedescriptor not valid anymore")
os.dup2(self.tmpfile_fd, self.targetfd)
self.syscapture.start()
self._state = "started"
def snap(self):
self.tmpfile.seek(0)
res = self.tmpfile.read()
self.tmpfile.seek(0)
self.tmpfile.truncate()
return res
def _done(self):
""" stop capturing, restore streams, return original capture file,
seeked to position zero. """
targetfd_save = self.__dict__.pop("targetfd_save")
os.dup2(targetfd_save, self.targetfd)
os.close(targetfd_save)
self.syscapture.done()
self.tmpfile.close()
self._state = "done"
def suspend(self):
self.syscapture.suspend()
os.dup2(self.targetfd_save, self.targetfd)
self._state = "suspended"
def resume(self):
self.syscapture.resume()
os.dup2(self.tmpfile_fd, self.targetfd)
self._state = "resumed"
def writeorg(self, data):
""" write to original file descriptor. """
if isinstance(data, str):
data = data.encode("utf8") # XXX use encoding of original stream
os.write(self.targetfd_save, data)
class FDCapture(FDCaptureBinary):
"""Capture IO to/from a given os-level filedescriptor.
snap() produces text
"""
# Ignore type because it doesn't match the type in the superclass (bytes).
EMPTY_BUFFER = str() # type: ignore
def snap(self):
res = super().snap()
enc = getattr(self.tmpfile, "encoding", None)
if enc and isinstance(res, bytes):
res = str(res, enc, "replace")
return res
class SysCaptureBinary:
CLOSE_STDIN = CLOSE_STDIN
EMPTY_BUFFER = b""
_state = None
def __init__(self, fd, tmpfile=None, stdin=CLOSE_STDIN):
name = patchsysdict[fd]
self._old = getattr(sys, name)
self.name = name
if tmpfile is None:
if name == "stdin":
if stdin is self.CLOSE_STDIN:
tmpfile = DontReadFromInput()
else:
tmpfile = stdin
else:
tmpfile = CaptureIO()
self.tmpfile = tmpfile
def __repr__(self):
return "<{} {} _old={} _state={!r} tmpfile={!r}>".format(
self.__class__.__name__,
self.name,
hasattr(self, "_old") and repr(self._old) or "<UNSET>",
self._state,
self.tmpfile,
)
def start(self):
setattr(sys, self.name, self.tmpfile)
self._state = "started"
def snap(self):
res = self.tmpfile.buffer.getvalue()
self.tmpfile.seek(0)
self.tmpfile.truncate()
return res
def done(self):
setattr(sys, self.name, self._old)
del self._old
self.tmpfile.close()
self._state = "done"
def suspend(self):
setattr(sys, self.name, self._old)
self._state = "suspended"
def resume(self):
setattr(sys, self.name, self.tmpfile)
self._state = "resumed"
def writeorg(self, data: bytes) -> None:
self._old.write(data.decode(self._old.encoding))
self._old.flush()
class SysCapture(SysCaptureBinary):
EMPTY_BUFFER = str() # type: ignore[assignment]
def snap(self):
res = self.tmpfile.getvalue()
self.tmpfile.seek(0)
self.tmpfile.truncate()
return res
def writeorg(self, data: str) -> None: # type: ignore
self._old.write(data)
self._old.flush()
class TeeSysCapture(SysCapture):
def __init__(self, fd, tmpfile=None):
name = patchsysdict[fd]
self._old = getattr(sys, name)
self.name = name
if tmpfile is None:
if name == "stdin":
tmpfile = DontReadFromInput()
else:
tmpfile = CaptureAndPassthroughIO(self._old)
self.tmpfile = tmpfile
map_fixname_class = {
"capfd": FDCapture,
"capfdbinary": FDCaptureBinary,
"capsys": SysCapture,
"capsysbinary": SysCaptureBinary,
}
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):
raise UnsupportedOperation("redirected stdin is pseudofile, has no fileno()")
def isatty(self):
return False
def close(self):
pass
@property
def buffer(self):
return self
def _colorama_workaround():
"""
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 _readline_workaround():
"""
Ensure readline is imported so that it attaches to the correct stdio
handles on Windows.
Pdb uses readline support where available--when not running from the Python
prompt, the readline module is not imported until running the pdb REPL. If
running pytest with the --pdb option this means the readline module is not
imported until after I/O capture has been started.
This is a problem for pyreadline, which is often used to implement readline
support on Windows, as it does not attach to the correct handles for stdout
and/or stdin if they have been redirected by the FDCapture mechanism. This
workaround ensures that readline is imported before I/O capture is setup so
that it can attach to the actual stdin/out for the console.
See https://github.com/pytest-dev/pytest/pull/1281
"""
if sys.platform.startswith("win32"):
try:
import readline # noqa: F401
except ImportError:
pass
def _py36_windowsconsoleio_workaround(stream):
"""
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 sys.version_info[:2] < (3, 6)
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"):
return
buffered = hasattr(stream.buffer, "raw")
raw_stdout = stream.buffer.raw if buffered else stream.buffer
if not isinstance(raw_stdout, io._WindowsConsoleIO):
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),
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")
