1. Ronny Pfannschmidt
  2. pytest-capture-refactor

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Ronny Pfannschmidt  committed 38769d2

initial code import for capture transfer

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File _pytest/capture.py

View file
-""" per-test stdout/stderr capturing mechanisms, ``capsys`` and ``capfd`` function arguments.  """
-
-import pytest, py
+"""
+    per-test stdout/stderr capturing mechanisms,
+    ``capsys`` and ``capfd`` function arguments.
+"""
 import sys
 import os
+import py
+import pytest
+
 
 def pytest_addoption(parser):
     group = parser.getgroup("general")
-    group._addoption('--capture', action="store", default=None,
+    group._addoption(
+        '--capture', action="store", default=None,
         metavar="method", choices=['fd', 'sys', 'no'],
         help="per-test capturing method: one of fd (default)|sys|no.")
-    group._addoption('-s', action="store_const", const="no", dest="capture",
+    group._addoption(
+        '-s', action="store_const", const="no", dest="capture",
         help="shortcut for --capture=no.")
 
+
 @pytest.mark.tryfirst
 def pytest_load_initial_conftests(early_config, parser, args, __multicall__):
     ns = parser.parse_known_args(args)
 
     def close(self):
         self._finalize()
+import os
+import sys
+import py
+import tempfile
+
+try:
+    from io import StringIO
+except ImportError:
+    from StringIO import StringIO
+
+if sys.version_info < (3,0):
+    class TextIO(StringIO):
+        def write(self, data):
+            if not isinstance(data, unicode):
+                data = unicode(data, getattr(self, '_encoding', 'UTF-8'), 'replace')
+            StringIO.write(self, data)
+else:
+    TextIO = StringIO
+
+try:
+    from io import BytesIO
+except ImportError:
+    class BytesIO(StringIO):
+        def write(self, data):
+            if isinstance(data, unicode):
+                raise TypeError("not a byte value: %r" %(data,))
+            StringIO.write(self, data)
+
+patchsysdict = {0: 'stdin', 1: 'stdout', 2: 'stderr'}
+
+class FDCapture:
+    """ Capture IO to/from a given os-level filedescriptor. """
+
+    def __init__(self, targetfd, tmpfile=None, now=True, patchsys=False):
+        """ save targetfd descriptor, and open a new
+            temporary file there.  If no tmpfile is
+            specified a tempfile.Tempfile() will be opened
+            in text mode.
+        """
+        self.targetfd = targetfd
+        if tmpfile is None and targetfd != 0:
+            f = tempfile.TemporaryFile('wb+')
+            tmpfile = dupfile(f, encoding="UTF-8")
+            f.close()
+        self.tmpfile = tmpfile
+        self._savefd = os.dup(self.targetfd)
+        if patchsys:
+            self._oldsys = getattr(sys, patchsysdict[targetfd])
+        if now:
+            self.start()
+
+    def start(self):
+        try:
+            os.fstat(self._savefd)
+        except OSError:
+            raise ValueError("saved filedescriptor not valid, "
+                "did you call start() twice?")
+        if self.targetfd == 0 and not self.tmpfile:
+            fd = os.open(devnullpath, os.O_RDONLY)
+            os.dup2(fd, 0)
+            os.close(fd)
+            if hasattr(self, '_oldsys'):
+                setattr(sys, patchsysdict[self.targetfd], DontReadFromInput())
+        else:
+            os.dup2(self.tmpfile.fileno(), self.targetfd)
+            if hasattr(self, '_oldsys'):
+                setattr(sys, patchsysdict[self.targetfd], self.tmpfile)
+
+    def done(self):
+        """ unpatch and clean up, returns the self.tmpfile (file object)
+        """
+        os.dup2(self._savefd, self.targetfd)
+        os.close(self._savefd)
+        if self.targetfd != 0:
+            self.tmpfile.seek(0)
+        if hasattr(self, '_oldsys'):
+            setattr(sys, patchsysdict[self.targetfd], self._oldsys)
+        return self.tmpfile
+
+    def writeorg(self, data):
+        """ write a string to the original file descriptor
+        """
+        tempfp = tempfile.TemporaryFile()
+        try:
+            os.dup2(self._savefd, tempfp.fileno())
+            tempfp.write(data)
+        finally:
+            tempfp.close()
+
+
+def dupfile(f, mode=None, buffering=0, raising=False, encoding=None):
+    """ return a new open file object that's a duplicate of f
+
+        mode is duplicated if not given, 'buffering' controls
+        buffer size (defaulting to no buffering) and 'raising'
+        defines whether an exception is raised when an incompatible
+        file object is passed in (if raising is False, the file
+        object itself will be returned)
+    """
+    try:
+        fd = f.fileno()
+        mode = mode or f.mode
+    except AttributeError:
+        if raising:
+            raise
+        return f
+    newfd = os.dup(fd)
+    if sys.version_info >= (3,0):
+        if encoding is not None:
+            mode = mode.replace("b", "")
+            buffering = True
+        return os.fdopen(newfd, mode, buffering, encoding, closefd=True)
+    else:
+        f = os.fdopen(newfd, mode, buffering)
+        if encoding is not None:
+            return EncodedFile(f, encoding)
+        return f
+
+class EncodedFile(object):
+    def __init__(self, _stream, encoding):
+        self._stream = _stream
+        self.encoding = encoding
+
+    def write(self, obj):
+        if isinstance(obj, unicode):
+            obj = obj.encode(self.encoding)
+        elif isinstance(obj, str):
+            pass
+        else:
+            obj = str(obj)
+        self._stream.write(obj)
+
+    def writelines(self, linelist):
+        data = ''.join(linelist)
+        self.write(data)
+
+    def __getattr__(self, name):
+        return getattr(self._stream, name)
+
+class Capture(object):
+    def call(cls, func, *args, **kwargs):
+        """ return a (res, out, err) tuple where
+            out and err represent the output/error output
+            during function execution.
+            call the given function with args/kwargs
+            and capture output/error during its execution.
+        """
+        so = cls()
+        try:
+            res = func(*args, **kwargs)
+        finally:
+            out, err = so.reset()
+        return res, out, err
+    call = classmethod(call)
+
+    def reset(self):
+        """ reset sys.stdout/stderr and return captured output as strings. """
+        if hasattr(self, '_reset'):
+            raise ValueError("was already reset")
+        self._reset = True
+        outfile, errfile = self.done(save=False)
+        out, err = "", ""
+        if outfile and not outfile.closed:
+            out = outfile.read()
+            outfile.close()
+        if errfile and errfile != outfile and not errfile.closed:
+            err = errfile.read()
+            errfile.close()
+        return out, err
+
+    def suspend(self):
+        """ return current snapshot captures, memorize tempfiles. """
+        outerr = self.readouterr()
+        outfile, errfile = self.done()
+        return outerr
+
+
+class StdCaptureFD(Capture):
+    """ This class allows to capture writes to FD1 and FD2
+        and may connect a NULL file to FD0 (and prevent
+        reads from sys.stdin).  If any of the 0,1,2 file descriptors
+        is invalid it will not be captured.
+    """
+    def __init__(self, out=True, err=True, mixed=False,
+        in_=True, patchsys=True, now=True):
+        self._options = {
+            "out": out,
+            "err": err,
+            "mixed": mixed,
+            "in_": in_,
+            "patchsys": patchsys,
+            "now": now,
+        }
+        self._save()
+        if now:
+            self.startall()
+
+    def _save(self):
+        in_ = self._options['in_']
+        out = self._options['out']
+        err = self._options['err']
+        mixed = self._options['mixed']
+        patchsys = self._options['patchsys']
+        if in_:
+            try:
+                self.in_ = FDCapture(0, tmpfile=None, now=False,
+                    patchsys=patchsys)
+            except OSError:
+                pass
+        if out:
+            tmpfile = None
+            if hasattr(out, 'write'):
+                tmpfile = out
+            try:
+                self.out = FDCapture(1, tmpfile=tmpfile,
+                           now=False, patchsys=patchsys)
+                self._options['out'] = self.out.tmpfile
+            except OSError:
+                pass
+        if err:
+            if out and mixed:
+                tmpfile = self.out.tmpfile
+            elif hasattr(err, 'write'):
+                tmpfile = err
+            else:
+                tmpfile = None
+            try:
+                self.err = FDCapture(2, tmpfile=tmpfile,
+                           now=False, patchsys=patchsys)
+                self._options['err'] = self.err.tmpfile
+            except OSError:
+                pass
+
+    def startall(self):
+        if hasattr(self, 'in_'):
+            self.in_.start()
+        if hasattr(self, 'out'):
+            self.out.start()
+        if hasattr(self, 'err'):
+            self.err.start()
+
+    def resume(self):
+        """ resume capturing with original temp files. """
+        self.startall()
+
+    def done(self, save=True):
+        """ return (outfile, errfile) and stop capturing. """
+        outfile = errfile = None
+        if hasattr(self, 'out') and not self.out.tmpfile.closed:
+            outfile = self.out.done()
+        if hasattr(self, 'err') and not self.err.tmpfile.closed:
+            errfile = self.err.done()
+        if hasattr(self, 'in_'):
+            tmpfile = self.in_.done()
+        if save:
+            self._save()
+        return outfile, errfile
+
+    def readouterr(self):
+        """ return snapshot value of stdout/stderr capturings. """
+        if hasattr(self, "out"):
+            out = self._readsnapshot(self.out.tmpfile)
+        else:
+            out = ""
+        if hasattr(self, "err"):
+            err = self._readsnapshot(self.err.tmpfile)
+        else:
+            err = ""
+        return [out, err]
+
+    def _readsnapshot(self, f):
+        f.seek(0)
+        res = f.read()
+        enc = getattr(f, "encoding", None)
+        if enc:
+            res = py.builtin._totext(res, enc, "replace")
+        f.truncate(0)
+        f.seek(0)
+        return res
+
+
+class StdCapture(Capture):
+    """ This class allows to capture writes to sys.stdout|stderr "in-memory"
+        and will raise errors on tries to read from sys.stdin. It only
+        modifies sys.stdout|stderr|stdin attributes and does not
+        touch underlying File Descriptors (use StdCaptureFD for that).
+    """
+    def __init__(self, out=True, err=True, in_=True, mixed=False, now=True):
+        self._oldout = sys.stdout
+        self._olderr = sys.stderr
+        self._oldin  = sys.stdin
+        if out and not hasattr(out, 'file'):
+            out = TextIO()
+        self.out = out
+        if err:
+            if mixed:
+                err = out
+            elif not hasattr(err, 'write'):
+                err = TextIO()
+        self.err = err
+        self.in_ = in_
+        if now:
+            self.startall()
+
+    def startall(self):
+        if self.out:
+            sys.stdout = self.out
+        if self.err:
+            sys.stderr = self.err
+        if self.in_:
+            sys.stdin  = self.in_  = DontReadFromInput()
+
+    def done(self, save=True):
+        """ return (outfile, errfile) and stop capturing. """
+        outfile = errfile = None
+        if self.out and not self.out.closed:
+            sys.stdout = self._oldout
+            outfile = self.out
+            outfile.seek(0)
+        if self.err and not self.err.closed:
+            sys.stderr = self._olderr
+            errfile = self.err
+            errfile.seek(0)
+        if self.in_:
+            sys.stdin = self._oldin
+        return outfile, errfile
+
+    def resume(self):
+        """ resume capturing with original temp files. """
+        self.startall()
+
+    def readouterr(self):
+        """ return snapshot value of stdout/stderr capturings. """
+        out = err = ""
+        if self.out:
+            out = self.out.getvalue()
+            self.out.truncate(0)
+            self.out.seek(0)
+        if self.err:
+            err = self.err.getvalue()
+            self.err.truncate(0)
+            self.err.seek(0)
+        return out, err
+
+class DontReadFromInput:
+    """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.
+    """
+    def read(self, *args):
+        raise IOError("reading from stdin while output is captured")
+    readline = read
+    readlines = read
+    __iter__ = read
+
+    def fileno(self):
+        raise ValueError("redirected Stdin is pseudofile, has no fileno()")
+    def isatty(self):
+        return False
+    def close(self):
+        pass
+
+try:
+    devnullpath = os.devnull
+except AttributeError:
+    if os.name == 'nt':
+        devnullpath = 'NUL'
+    else:
+        devnullpath = '/dev/null'

File testing/test_capture.py

View file
-import pytest, py, os, sys
+from __future__ import with_statement
+import os
+import sys
+import py
+import pytest
+
 from _pytest.capture import CaptureManager
 
 needsosdup = pytest.mark.xfail("not hasattr(os, 'dup')")
 
 @pytest.mark.xfail(sys.version_info >= (3, 0), reason='encoding issues')
 def test_capture_binary_output(testdir):
-    testdir.makepyfile("""
+    testdir.makepyfile(r"""
         import pytest
 
         def test_a():
         '*2 passed*',
     ])
     
+
+import os, sys
+import py
+
+needsdup = py.test.mark.skipif("not hasattr(os, 'dup')")
+
+from py.builtin import print_
+
+if sys.version_info >= (3,0):
+    def tobytes(obj):
+        if isinstance(obj, str):
+            obj = obj.encode('UTF-8')
+        assert isinstance(obj, bytes)
+        return obj
+    def totext(obj):
+        if isinstance(obj, bytes):
+            obj = str(obj, 'UTF-8')
+        assert isinstance(obj, str)
+        return obj
+else:
+    def tobytes(obj):
+        if isinstance(obj, unicode):
+            obj = obj.encode('UTF-8')
+        assert isinstance(obj, str)
+        return obj
+    def totext(obj):
+        if isinstance(obj, str):
+            obj = unicode(obj, 'UTF-8')
+        assert isinstance(obj, unicode)
+        return obj
+
+def oswritebytes(fd, obj):
+    os.write(fd, tobytes(obj))
+
+class TestTextIO:
+    def test_text(self):
+        f = py.io.TextIO()
+        f.write("hello")
+        s = f.getvalue()
+        assert s == "hello"
+        f.close()
+
+    def test_unicode_and_str_mixture(self):
+        f = py.io.TextIO()
+        if sys.version_info >= (3,0):
+            f.write("\u00f6")
+            py.test.raises(TypeError, "f.write(bytes('hello', 'UTF-8'))")
+        else:
+            f.write(unicode("\u00f6", 'UTF-8'))
+            f.write("hello") # bytes
+            s = f.getvalue()
+            f.close()
+            assert isinstance(s, unicode)
+
+def test_bytes_io():
+    f = py.io.BytesIO()
+    f.write(tobytes("hello"))
+    py.test.raises(TypeError, "f.write(totext('hello'))")
+    s = f.getvalue()
+    assert s == tobytes("hello")
+
+def test_dontreadfrominput():
+    from py._io.capture import DontReadFromInput
+    f = DontReadFromInput()
+    assert not f.isatty()
+    py.test.raises(IOError, f.read)
+    py.test.raises(IOError, f.readlines)
+    py.test.raises(IOError, iter, f)
+    py.test.raises(ValueError, f.fileno)
+    f.close() # just for completeness
+
+def pytest_funcarg__tmpfile(request):
+    testdir = request.getfuncargvalue("testdir")
+    f = testdir.makepyfile("").open('wb+')
+    request.addfinalizer(f.close)
+    return f
+
+@needsdup
+def test_dupfile(tmpfile):
+    flist = []
+    for i in range(5):
+        nf = py.io.dupfile(tmpfile, encoding="utf-8")
+        assert nf != tmpfile
+        assert nf.fileno() != tmpfile.fileno()
+        assert nf not in flist
+        print_(i, end="", file=nf)
+        flist.append(nf)
+    for i in range(5):
+        f = flist[i]
+        f.close()
+    tmpfile.seek(0)
+    s = tmpfile.read()
+    assert "01234" in repr(s)
+    tmpfile.close()
+
+def test_dupfile_no_mode():
+    """
+    dupfile should trap an AttributeError and return f if no mode is supplied.
+    """
+    class SomeFileWrapper(object):
+        "An object with a fileno method but no mode attribute"
+        def fileno(self):
+            return 1
+    tmpfile = SomeFileWrapper()
+    assert py.io.dupfile(tmpfile) is tmpfile
+    with py.test.raises(AttributeError):
+        py.io.dupfile(tmpfile, raising=True)
+
+def lsof_check(func):
+    pid = os.getpid()
+    try:
+        out = py.process.cmdexec("lsof -p %d" % pid)
+    except py.process.cmdexec.Error:
+        py.test.skip("could not run 'lsof'")
+    func()
+    out2 = py.process.cmdexec("lsof -p %d" % pid)
+    len1 = len([x for x in out.split("\n") if "REG" in x])
+    len2 = len([x for x in out2.split("\n") if "REG" in x])
+    assert len2 < len1 + 3, out2
+
+class TestFDCapture:
+    pytestmark = needsdup
+
+    def test_not_now(self, tmpfile):
+        fd = tmpfile.fileno()
+        cap = py.io.FDCapture(fd, now=False)
+        data = tobytes("hello")
+        os.write(fd, data)
+        f = cap.done()
+        s = f.read()
+        assert not s
+        cap = py.io.FDCapture(fd, now=False)
+        cap.start()
+        os.write(fd, data)
+        f = cap.done()
+        s = f.read()
+        assert s == "hello"
+
+    def test_simple(self, tmpfile):
+        fd = tmpfile.fileno()
+        cap = py.io.FDCapture(fd)
+        data = tobytes("hello")
+        os.write(fd, data)
+        f = cap.done()
+        s = f.read()
+        assert s == "hello"
+        f.close()
+
+    def test_simple_many(self, tmpfile):
+        for i in range(10):
+            self.test_simple(tmpfile)
+
+    def test_simple_many_check_open_files(self, tmpfile):
+        lsof_check(lambda: self.test_simple_many(tmpfile))
+
+    def test_simple_fail_second_start(self, tmpfile):
+        fd = tmpfile.fileno()
+        cap = py.io.FDCapture(fd)
+        f = cap.done()
+        py.test.raises(ValueError, cap.start)
+        f.close()
+
+    def test_stderr(self):
+        cap = py.io.FDCapture(2, patchsys=True)
+        print_("hello", file=sys.stderr)
+        f = cap.done()
+        s = f.read()
+        assert s == "hello\n"
+
+    def test_stdin(self, tmpfile):
+        tmpfile.write(tobytes("3"))
+        tmpfile.seek(0)
+        cap = py.io.FDCapture(0, tmpfile=tmpfile)
+        # check with os.read() directly instead of raw_input(), because
+        # sys.stdin itself may be redirected (as py.test now does by default)
+        x = os.read(0, 100).strip()
+        f = cap.done()
+        assert x == tobytes("3")
+
+    def test_writeorg(self, tmpfile):
+        data1, data2 = tobytes("foo"), tobytes("bar")
+        try:
+            cap = py.io.FDCapture(tmpfile.fileno())
+            tmpfile.write(data1)
+            cap.writeorg(data2)
+        finally:
+            tmpfile.close()
+        f = cap.done()
+        scap = f.read()
+        assert scap == totext(data1)
+        stmp = open(tmpfile.name, 'rb').read()
+        assert stmp == data2
+
+
+class TestStdCapture:
+    def getcapture(self, **kw):
+        return py.io.StdCapture(**kw)
+
+    def test_capturing_done_simple(self):
+        cap = self.getcapture()
+        sys.stdout.write("hello")
+        sys.stderr.write("world")
+        outfile, errfile = cap.done()
+        s = outfile.read()
+        assert s == "hello"
+        s = errfile.read()
+        assert s == "world"
+
+    def test_capturing_reset_simple(self):
+        cap = self.getcapture()
+        print("hello world")
+        sys.stderr.write("hello error\n")
+        out, err = cap.reset()
+        assert out == "hello world\n"
+        assert err == "hello error\n"
+
+    def test_capturing_readouterr(self):
+        cap = self.getcapture()
+        try:
+            print ("hello world")
+            sys.stderr.write("hello error\n")
+            out, err = cap.readouterr()
+            assert out == "hello world\n"
+            assert err == "hello error\n"
+            sys.stderr.write("error2")
+        finally:
+            out, err = cap.reset()
+        assert err == "error2"
+
+    def test_capturing_readouterr_unicode(self):
+        cap = self.getcapture()
+        print ("hx\xc4\x85\xc4\x87")
+        out, err = cap.readouterr()
+        assert out == py.builtin._totext("hx\xc4\x85\xc4\x87\n", "utf8")
+
+    @py.test.mark.skipif('sys.version_info >= (3,)',
+                      reason='text output different for bytes on python3')
+    def test_capturing_readouterr_decode_error_handling(self):
+        cap = self.getcapture()
+        # triggered a internal error in pytest
+        print('\xa6')
+        out, err = cap.readouterr()
+        assert out == py.builtin._totext('\ufffd\n', 'unicode-escape')
+
+    def test_capturing_mixed(self):
+        cap = self.getcapture(mixed=True)
+        sys.stdout.write("hello ")
+        sys.stderr.write("world")
+        sys.stdout.write(".")
+        out, err = cap.reset()
+        assert out.strip() == "hello world."
+        assert not err
+
+    def test_reset_twice_error(self):
+        cap = self.getcapture()
+        print ("hello")
+        out, err = cap.reset()
+        py.test.raises(ValueError, cap.reset)
+        assert out == "hello\n"
+        assert not err
+
+    def test_capturing_modify_sysouterr_in_between(self):
+        oldout = sys.stdout
+        olderr = sys.stderr
+        cap = self.getcapture()
+        sys.stdout.write("hello")
+        sys.stderr.write("world")
+        sys.stdout = py.io.TextIO()
+        sys.stderr = py.io.TextIO()
+        print ("not seen")
+        sys.stderr.write("not seen\n")
+        out, err = cap.reset()
+        assert out == "hello"
+        assert err == "world"
+        assert sys.stdout == oldout
+        assert sys.stderr == olderr
+
+    def test_capturing_error_recursive(self):
+        cap1 = self.getcapture()
+        print ("cap1")
+        cap2 = self.getcapture()
+        print ("cap2")
+        out2, err2 = cap2.reset()
+        out1, err1 = cap1.reset()
+        assert out1 == "cap1\n"
+        assert out2 == "cap2\n"
+
+    def test_just_out_capture(self):
+        cap = self.getcapture(out=True, err=False)
+        sys.stdout.write("hello")
+        sys.stderr.write("world")
+        out, err = cap.reset()
+        assert out == "hello"
+        assert not err
+
+    def test_just_err_capture(self):
+        cap = self.getcapture(out=False, err=True)
+        sys.stdout.write("hello")
+        sys.stderr.write("world")
+        out, err = cap.reset()
+        assert err == "world"
+        assert not out
+
+    def test_stdin_restored(self):
+        old = sys.stdin
+        cap = self.getcapture(in_=True)
+        newstdin = sys.stdin
+        out, err = cap.reset()
+        assert newstdin != sys.stdin
+        assert sys.stdin is old
+
+    def test_stdin_nulled_by_default(self):
+        print ("XXX this test may well hang instead of crashing")
+        print ("XXX which indicates an error in the underlying capturing")
+        print ("XXX mechanisms")
+        cap = self.getcapture()
+        py.test.raises(IOError, "sys.stdin.read()")
+        out, err = cap.reset()
+
+    def test_suspend_resume(self):
+        cap = self.getcapture(out=True, err=False, in_=False)
+        try:
+            print ("hello")
+            sys.stderr.write("error\n")
+            out, err = cap.suspend()
+            assert out == "hello\n"
+            assert not err
+            print ("in between")
+            sys.stderr.write("in between\n")
+            cap.resume()
+            print ("after")
+            sys.stderr.write("error_after\n")
+        finally:
+            out, err = cap.reset()
+        assert out == "after\n"
+        assert not err
+
+class TestStdCaptureNotNow(TestStdCapture):
+    def getcapture(self, **kw):
+        kw['now'] = False
+        cap = py.io.StdCapture(**kw)
+        cap.startall()
+        return cap
+
+class TestStdCaptureFD(TestStdCapture):
+    pytestmark = needsdup
+
+    def getcapture(self, **kw):
+        return py.io.StdCaptureFD(**kw)
+
+    def test_intermingling(self):
+        cap = self.getcapture()
+        oswritebytes(1, "1")
+        sys.stdout.write(str(2))
+        sys.stdout.flush()
+        oswritebytes(1, "3")
+        oswritebytes(2, "a")
+        sys.stderr.write("b")
+        sys.stderr.flush()
+        oswritebytes(2, "c")
+        out, err = cap.reset()
+        assert out == "123"
+        assert err == "abc"
+
+    def test_callcapture(self):
+        def func(x, y):
+            print (x)
+            py.std.sys.stderr.write(str(y))
+            return 42
+
+        res, out, err = py.io.StdCaptureFD.call(func, 3, y=4)
+        assert res == 42
+        assert out.startswith("3")
+        assert err.startswith("4")
+
+    def test_many(self, capfd):
+        def f():
+            for i in range(10):
+                cap = py.io.StdCaptureFD()
+                cap.reset()
+        lsof_check(f)
+
+class TestStdCaptureFDNotNow(TestStdCaptureFD):
+    pytestmark = needsdup
+
+    def getcapture(self, **kw):
+        kw['now'] = False
+        cap = py.io.StdCaptureFD(**kw)
+        cap.startall()
+        return cap
+
+@needsdup
+def test_stdcapture_fd_tmpfile(tmpfile):
+    capfd = py.io.StdCaptureFD(out=tmpfile)
+    os.write(1, "hello".encode("ascii"))
+    os.write(2, "world".encode("ascii"))
+    outf, errf = capfd.done()
+    assert outf == tmpfile
+
+class TestStdCaptureFDinvalidFD:
+    pytestmark = needsdup
+    def test_stdcapture_fd_invalid_fd(self, testdir):
+        testdir.makepyfile("""
+            import py, os
+            def test_stdout():
+                os.close(1)
+                cap = py.io.StdCaptureFD(out=True, err=False, in_=False)
+                cap.done()
+            def test_stderr():
+                os.close(2)
+                cap = py.io.StdCaptureFD(out=False, err=True, in_=False)
+                cap.done()
+            def test_stdin():
+                os.close(0)
+                cap = py.io.StdCaptureFD(out=False, err=False, in_=True)
+                cap.done()
+        """)
+        result = testdir.runpytest("--capture=fd")
+        assert result.ret == 0
+        assert result.parseoutcomes()['passed'] == 3
+
+def test_capture_not_started_but_reset():
+    capsys = py.io.StdCapture(now=False)
+    capsys.done()
+    capsys.done()
+    capsys.reset()
+
+@needsdup
+def test_capture_no_sys():
+    capsys = py.io.StdCapture()
+    try:
+        cap = py.io.StdCaptureFD(patchsys=False)
+        sys.stdout.write("hello")
+        sys.stderr.write("world")
+        oswritebytes(1, "1")
+        oswritebytes(2, "2")
+        out, err = cap.reset()
+        assert out == "1"
+        assert err == "2"
+    finally:
+        capsys.reset()
+
+@needsdup
+def test_callcapture_nofd():
+    def func(x, y):
+        oswritebytes(1, "hello")
+        oswritebytes(2, "hello")
+        print (x)
+        sys.stderr.write(str(y))
+        return 42
+
+    capfd = py.io.StdCaptureFD(patchsys=False)
+    try:
+        res, out, err = py.io.StdCapture.call(func, 3, y=4)
+    finally:
+        capfd.reset()
+    assert res == 42
+    assert out.startswith("3")
+    assert err.startswith("4")
+
+@needsdup
+@py.test.mark.parametrize('use', [True, False])
+def test_fdcapture_tmpfile_remains_the_same(tmpfile, use):
+    if not use:
+        tmpfile = True
+    cap = py.io.StdCaptureFD(out=False, err=tmpfile, now=False)
+    cap.startall()
+    capfile = cap.err.tmpfile
+    cap.suspend()
+    cap.resume()
+    capfile2 = cap.err.tmpfile
+    assert capfile2 == capfile
+
+@py.test.mark.parametrize('method', ['StdCapture', 'StdCaptureFD'])
+def test_capturing_and_logging_fundamentals(testdir, method):
+    if method == "StdCaptureFD" and not hasattr(os, 'dup'):
+        py.test.skip("need os.dup")
+    # here we check a fundamental feature
+    p = testdir.makepyfile("""
+        import sys, os
+        import py, logging
+        cap = py.io.%s(out=False, in_=False)
+
+        logging.warn("hello1")
+        outerr = cap.suspend()
+        print ("suspend, captured %%s" %%(outerr,))
+        logging.warn("hello2")
+
+        cap.resume()
+        logging.warn("hello3")
+
+        outerr = cap.suspend()
+        print ("suspend2, captured %%s" %% (outerr,))
+    """ % (method,))
+    result = testdir.runpython(p)
+    result.stdout.fnmatch_lines([
+        "suspend, captured*hello1*",
+        "suspend2, captured*hello2*WARNING:root:hello3*",
+    ])
+    assert "atexit" not in result.stderr.str()