Source code for nose2.plugins.buffer

Buffer stdout and/or stderr during test execution, appending any
output to the error reports of failed tests.

This allows you to use print for debugging in tests without making
your test runs noisy.

This plugin implements :func:`startTest`, :func:`stopTest`,
:func:`setTestOutcome`, :func:`outcomeDetail`, :func:`beforeInteraction`
and :func:`afterInteraction` to manage capturing sys.stdout and/or
sys.stderr into buffers, attaching the buffered output to test error
report detail, and getting out of the way when other plugins want to
talk to the user.


import io
import sys

from nose2 import events
from nose2.util import ln

__unittest = True

class _Buffer:
    def __init__(self, stream):
        self._stream = stream
        self._buffer = io.StringIO()

    def fileno(self):
        return self._stream.fileno()

    def __getattr__(self, attr):
        # this happens on unpickling
        if attr == "_buffer":
            raise AttributeError("No _buffer yet")
        return getattr(self._buffer, attr)

    def __le__(self, obj):
        return self._buffer.getvalue() == obj

    def __eq__(self, obj):
        return self._buffer.getvalue() == obj

    def __str__(self):
        return self._buffer.getvalue()

    def __repr__(self):
        return repr(self._buffer.getvalue())

[docs]class OutputBufferPlugin(events.Plugin): """Buffer output during test execution""" commandLineSwitch = ("B", "output-buffer", "Enable output buffer") configSection = "output-buffer" def __init__(self): self.captureStdout = self.config.as_bool("stdout", default=True) self.captureStderr = self.config.as_bool("stderr", default=False) self.bufStdout = self.bufStderr = None self.realStdout = sys.__stdout__ self.realStderr = sys.__stderr__ self._disable = False def registerInSubprocess(self, event): event.pluginClasses.append(self.__class__) # turn off in this process: the subproc will run the tests self._disable = True def startSubprocess(self, event): self.realStdout = sys.__stdout__ self.realStderr = sys.__stderr__
[docs] def startTest(self, event): """Start buffering selected stream(s)""" self._buffer()
[docs] def stopTest(self, event): """Stop buffering""" self._restore()
def _get_stream_unicode_save(self, stream, buffer): buf = buffer.getvalue() return "\n".join( [ ln(f">> begin captured {stream} <<"), buf, ln(f">> end captured {stream} <<"), ] )
[docs] def setTestOutcome(self, event): """Attach buffer(s) to event.metadata""" if self._disable: return if self.captureStdout and "stdout" not in event.metadata: event.metadata["stdout"] = self._get_stream_unicode_save( "stdout", self.bufStdout ) if self.captureStderr and "stderr" not in event.metadata: event.metadata["stderr"] = self._get_stream_unicode_save( "stderr", self.bufStderr )
[docs] def outcomeDetail(self, event): """Add buffered output to event.extraDetail""" for stream in ("stdout", "stderr"): if stream in event.outcomeEvent.metadata: b = event.outcomeEvent.metadata[stream] if b: event.extraDetail.append(b)
[docs] def beforeInteraction(self, event): """Stop buffering so users can see stdout""" self._restore()
[docs] def afterInteraction(self, event): """Start buffering again (does not clear buffers)""" self._buffer(fresh=False)
def stopSubprocess(self, event): self._restore() def _restore(self): if self._disable: return if self.captureStdout: sys.stdout = self.realStdout if self.captureStderr: sys.stderr = self.realStderr def _buffer(self, fresh=True): if self._disable: return if self.captureStdout: if fresh or self.bufStdout is None: self.bufStdout = _Buffer(sys.stdout) sys.stdout = self.bufStdout if self.captureStderr: if fresh or self.bufStderr is None: self.bufStderr = _Buffer(sys.stderr) sys.stderr = self.bufStderr