""" per-test stdout/stderr capturing mechanism. """ from __future__ import absolute_import, division, print_function import collections import contextlib import sys import os import io from io import UnsupportedOperation from tempfile import TemporaryFile import six import pytest from _pytest.compat import CaptureIO patchsysdict = {0: 'stdin', 1: 'stdout', 2: 'stderr'} 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'], help="per-test capturing method: one of fd|sys|no.") 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, parser, args): 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) # make sure logging does not raise exceptions at the end def silence_logging_at_shutdown(): if "logging" in sys.modules: sys.modules["logging"].raiseExceptions = False early_config.add_cleanup(silence_logging_at_shutdown) # finally trigger conftest loading but while capturing (issue93) capman.start_global_capturing() outcome = yield out, err = capman.suspend_global_capture() if outcome.excinfo is not None: sys.stdout.write(out) sys.stderr.write(err) class CaptureManager(object): """ 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): self._method = method self._global_capturing = None def _getcapture(self, method): 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) else: raise ValueError("unknown capturing method: %r" % method) def start_global_capturing(self): assert self._global_capturing is None self._global_capturing = self._getcapture(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): self._global_capturing.resume_capturing() def suspend_global_capture(self, item=None, in_=False): if item is not None: self.deactivate_fixture(item) cap = getattr(self, "_global_capturing", None) if cap is not None: try: outerr = cap.readouterr() finally: cap.suspend_capturing(in_=in_) return outerr def activate_fixture(self, item): """If the current item is using ``capsys`` or ``capfd``, activate them so they take precedence over the global capture. """ fixture = getattr(item, "_capture_fixture", None) if fixture is not None: fixture._start() def deactivate_fixture(self, item): """Deactivates the ``capsys`` or ``capfd`` fixture of this item, if any.""" fixture = getattr(item, "_capture_fixture", None) if fixture is not None: fixture.close() @pytest.hookimpl(hookwrapper=True) def pytest_make_collect_report(self, collector): if isinstance(collector, pytest.File): self.resume_global_capture() outcome = yield out, err = self.suspend_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): self.resume_global_capture() # no need to activate a capture fixture because they activate themselves during creation; this # only makes sense when a fixture uses a capture fixture, otherwise the capture fixture will # be activated during pytest_runtest_call yield self.suspend_capture_item(item, "setup") @pytest.hookimpl(hookwrapper=True) def pytest_runtest_call(self, item): self.resume_global_capture() # it is important to activate this fixture during the call phase so it overwrites the "global" # capture self.activate_fixture(item) yield self.suspend_capture_item(item, "call") @pytest.hookimpl(hookwrapper=True) def pytest_runtest_teardown(self, item): self.resume_global_capture() self.activate_fixture(item) yield self.suspend_capture_item(item, "teardown") @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() def suspend_capture_item(self, item, when, in_=False): out, err = self.suspend_global_capture(item, in_=in_) item.add_report_section(when, "stdout", out) item.add_report_section(when, "stderr", err) capture_fixtures = {'capfd', 'capfdbinary', 'capsys', 'capsysbinary'} def _ensure_only_one_capture_fixture(request, name): fixtures = set(request.fixturenames) & capture_fixtures - set((name,)) if fixtures: fixtures = sorted(fixtures) fixtures = fixtures[0] if len(fixtures) == 1 else fixtures raise request.raiseerror( "cannot use {0} and {1} at the same time".format( fixtures, name, ), ) @pytest.fixture def capsys(request): """Enable capturing of writes to ``sys.stdout`` and ``sys.stderr`` and make captured output available via ``capsys.readouterr()`` method calls which return a ``(out, err)`` namedtuple. ``out`` and ``err`` will be ``text`` objects. """ _ensure_only_one_capture_fixture(request, 'capsys') with _install_capture_fixture_on_item(request, SysCapture) as fixture: yield fixture @pytest.fixture def capsysbinary(request): """Enable capturing of writes to ``sys.stdout`` and ``sys.stderr`` and make captured output available via ``capsys.readouterr()`` method calls which return a ``(out, err)`` tuple. ``out`` and ``err`` will be ``bytes`` objects. """ _ensure_only_one_capture_fixture(request, 'capsysbinary') # Currently, the implementation uses the python3 specific `.buffer` # property of CaptureIO. if sys.version_info < (3,): raise request.raiseerror('capsysbinary is only supported on python 3') with _install_capture_fixture_on_item(request, SysCaptureBinary) as fixture: yield fixture @pytest.fixture def capfd(request): """Enable capturing of writes to file descriptors ``1`` and ``2`` and make captured output available via ``capfd.readouterr()`` method calls which return a ``(out, err)`` tuple. ``out`` and ``err`` will be ``text`` objects. """ _ensure_only_one_capture_fixture(request, 'capfd') if not hasattr(os, 'dup'): pytest.skip("capfd fixture needs os.dup function which is not available in this system") with _install_capture_fixture_on_item(request, FDCapture) as fixture: yield fixture @pytest.fixture def capfdbinary(request): """Enable capturing of write to file descriptors 1 and 2 and make captured output available via ``capfdbinary.readouterr`` method calls which return a ``(out, err)`` tuple. ``out`` and ``err`` will be ``bytes`` objects. """ _ensure_only_one_capture_fixture(request, 'capfdbinary') if not hasattr(os, 'dup'): pytest.skip("capfdbinary fixture needs os.dup function which is not available in this system") with _install_capture_fixture_on_item(request, FDCaptureBinary) as fixture: yield fixture @contextlib.contextmanager def _install_capture_fixture_on_item(request, capture_class): """ Context manager which creates a ``CaptureFixture`` instance and "installs" it on the item/node of the given request. Used by ``capsys`` and ``capfd``. The CaptureFixture is added as attribute of the item because it needs to accessed by ``CaptureManager`` during its ``pytest_runtest_*`` hooks. """ request.node._capture_fixture = fixture = CaptureFixture(capture_class, request) capmanager = request.config.pluginmanager.getplugin('capturemanager') # need to active this fixture right away in case it is being used by another fixture (setup phase) # if this fixture is being used only by a test function (call phase), then we wouldn't need this # activation, but it doesn't hurt capmanager.activate_fixture(request.node) yield fixture fixture.close() del request.node._capture_fixture class CaptureFixture(object): """ 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 def _start(self): self._capture = MultiCapture(out=True, err=True, in_=False, Capture=self.captureclass) self._capture.start_capturing() def close(self): cap = self.__dict__.pop("_capture", None) if cap is not None: self._outerr = cap.pop_outerr_to_orig() cap.stop_capturing() 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 """ try: return self._capture.readouterr() except AttributeError: return self._outerr @contextlib.contextmanager def disabled(self): """Temporarily disables capture while inside the 'with' block.""" self._capture.suspend_capturing() capmanager = self.request.config.pluginmanager.getplugin('capturemanager') capmanager.suspend_global_capture(item=None, in_=False) try: yield finally: capmanager.resume_global_capture() self._capture.resume_capturing() def safe_text_dupfile(f, mode, default_encoding="UTF8"): """ return a 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(object): errors = "strict" # possibly needed by py3 code (issue555) def __init__(self, buffer, encoding): self.buffer = buffer self.encoding = encoding def write(self, obj): if isinstance(obj, six.text_type): obj = obj.encode(self.encoding, "replace") self.buffer.write(obj) def writelines(self, linelist): data = ''.join(linelist) self.write(data) @property def name(self): """Ensure that file.name is a string.""" return repr(self.buffer) def __getattr__(self, name): return getattr(object.__getattribute__(self, "buffer"), name) CaptureResult = collections.namedtuple("CaptureResult", ["out", "err"]) class MultiCapture(object): out = err = in_ = None 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 start_capturing(self): 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): 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): if self.out: self.out.resume() if self.err: self.err.resume() if hasattr(self, "_in_suspended"): self.in_.resume() del self._in_suspended def stop_capturing(self): """ stop capturing and reset capturing streams """ if hasattr(self, '_reset'): raise ValueError("was already stopped") self._reset = True 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(object): __init__ = start = done = suspend = resume = lambda *args: None class FDCaptureBinary(object): """Capture IO to/from a given os-level filedescriptor. snap() produces `bytes` """ 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: 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 "" % (self.targetfd, self.targetfd_save) 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() 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() def suspend(self): self.syscapture.suspend() os.dup2(self.targetfd_save, self.targetfd) def resume(self): self.syscapture.resume() os.dup2(self.tmpfile_fd, self.targetfd) def writeorg(self, data): """ write to original file descriptor. """ if isinstance(data, six.text_type): 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 """ def snap(self): res = FDCaptureBinary.snap(self) enc = getattr(self.tmpfile, "encoding", None) if enc and isinstance(res, bytes): res = six.text_type(res, enc, "replace") return res class SysCapture(object): 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 = CaptureIO() self.tmpfile = tmpfile def start(self): setattr(sys, self.name, self.tmpfile) def snap(self): res = self.tmpfile.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() def suspend(self): setattr(sys, self.name, self._old) def resume(self): setattr(sys, self.name, self.tmpfile) def writeorg(self, data): self._old.write(data) self._old.flush() class SysCaptureBinary(SysCapture): def snap(self): res = self.tmpfile.buffer.getvalue() self.tmpfile.seek(0) self.tmpfile.truncate() return res class DontReadFromInput(object): """Temporary stub class. Ideally when stdin is accessed, the capturing should be turned off, with possibly all data captured so far sent to the screen. This should be configurable, though, because in automated test runs it is better to crash than hang indefinitely. """ encoding = None def read(self, *args): raise IOError("reading from stdin while output is captured") readline = read readlines = read __iter__ = read 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): if sys.version_info >= (3, 0): return self else: raise AttributeError('redirected stdin has no attribute buffer') 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 not sys.platform.startswith('win32'): return try: import colorama # noqa 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 not sys.platform.startswith('win32'): return try: import readline # noqa 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): 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__ = sys.stdin = _reopen_stdio(sys.stdin, 'rb') sys.__stdout__ = sys.stdout = _reopen_stdio(sys.stdout, 'wb') sys.__stderr__ = sys.stderr = _reopen_stdio(sys.stderr, 'wb')