Lib/test/test_support.py

"""Supporting definitions for the Python regression tests."""

if __name__ != 'test.test_support':
    raise ImportError('test_support must be imported from the test package')

import contextlib
import errno
import socket
import sys
import os
import os.path
import warnings
import types
import unittest

class Error(Exception):
    """Base class for regression test exceptions."""

class TestFailed(Error):
    """Test failed."""

class TestSkipped(Error):
    """Test skipped.

    This can be raised to indicate that a test was deliberatly
    skipped, but not because a feature wasn't available.  For
    example, if some resource can't be used, such as the network
    appears to be unavailable, this should be raised instead of
    TestFailed.
    """

class ResourceDenied(TestSkipped):
    """Test skipped because it requested a disallowed resource.

    This is raised when a test calls requires() for a resource that
    has not be enabled.  It is used to distinguish between expected
    and unexpected skips.
    """

verbose = 1              # Flag set to 0 by regrtest.py
use_resources = None     # Flag set to [] by regrtest.py
max_memuse = 0           # Disable bigmem tests (they will still be run with
                         # small sizes, to make sure they work.)

# _original_stdout is meant to hold stdout at the time regrtest began.
# This may be "the real" stdout, or IDLE's emulation of stdout, or whatever.
# The point is to have some flavor of stdout the user can actually see.
_original_stdout = None
def record_original_stdout(stdout):
    global _original_stdout
    _original_stdout = stdout

def get_original_stdout():
    return _original_stdout or sys.stdout

def unload(name):
    try:
        del sys.modules[name]
    except KeyError:
        pass

def unlink(filename):
    try:
        os.unlink(filename)
    except OSError:
        pass

def forget(modname):
    '''"Forget" a module was ever imported by removing it from sys.modules and
    deleting any .pyc and .pyo files.'''
    unload(modname)
    for dirname in sys.path:
        unlink(os.path.join(dirname, modname + '.pyc'))
        # Deleting the .pyo file cannot be within the 'try' for the .pyc since
        # the chance exists that there is no .pyc (and thus the 'try' statement
        # is exited) but there is a .pyo file.
        unlink(os.path.join(dirname, modname + '.pyo'))

def is_resource_enabled(resource):
    """Test whether a resource is enabled.  Known resources are set by
    regrtest.py."""
    return use_resources is not None and resource in use_resources

def requires(resource, msg=None):
    """Raise ResourceDenied if the specified resource is not available.

    If the caller's module is __main__ then automatically return True.  The
    possibility of False being returned occurs when regrtest.py is executing."""
    # see if the caller's module is __main__ - if so, treat as if
    # the resource was set
    if sys._getframe().f_back.f_globals.get("__name__") == "__main__":
        return
    if not is_resource_enabled(resource):
        if msg is None:
            msg = "Use of the `%s' resource not enabled" % resource
        raise ResourceDenied(msg)

def bind_port(sock, host='', preferred_port=54321):
    """Try to bind the sock to a port.  If we are running multiple
    tests and we don't try multiple ports, the test can fails.  This
    makes the test more robust."""

    # some random ports that hopefully no one is listening on.
    for port in [preferred_port, 9907, 10243, 32999]:
        try:
            sock.bind((host, port))
            return port
        except socket.error as e:
            (err, msg) = e.args
            if err != errno.EADDRINUSE:
                raise
            print('  WARNING: failed to listen on port %d, trying another' % port, file=sys.__stderr__)
    raise TestFailed('unable to find port to listen on')

FUZZ = 1e-6

def fcmp(x, y): # fuzzy comparison function
    if isinstance(x, float) or isinstance(y, float):
        try:
            fuzz = (abs(x) + abs(y)) * FUZZ
            if abs(x-y) <= fuzz:
                return 0
        except:
            pass
    elif type(x) == type(y) and isinstance(x, (tuple, list)):
        for i in range(min(len(x), len(y))):
            outcome = fcmp(x[i], y[i])
            if outcome != 0:
                return outcome
        return (len(x) > len(y)) - (len(x) < len(y))
    return (x > y) - (x < y)

try:
    str
    have_unicode = True
except NameError:
    have_unicode = False

is_jython = sys.platform.startswith('java')

# Filename used for testing
if os.name == 'java':
    # Jython disallows @ in module names
    TESTFN = '$test'
else:
    TESTFN = '@test'

    # Assuming sys.getfilesystemencoding()!=sys.getdefaultencoding()
    # TESTFN_UNICODE is a filename that can be encoded using the
    # file system encoding, but *not* with the default (ascii) encoding
    TESTFN_UNICODE = "@test-\xe0\xf2"
    TESTFN_ENCODING = sys.getfilesystemencoding()
    # TESTFN_UNICODE_UNENCODEABLE is a filename that should *not* be
    # able to be encoded by *either* the default or filesystem encoding.
    # This test really only makes sense on Windows NT platforms
    # which have special Unicode support in posixmodule.
    if (not hasattr(sys, "getwindowsversion") or
            sys.getwindowsversion()[3] < 2): #  0=win32s or 1=9x/ME
        TESTFN_UNICODE_UNENCODEABLE = None
    else:
        # Japanese characters (I think - from bug 846133)
        TESTFN_UNICODE_UNENCODEABLE = "@test-\u5171\u6709\u3055\u308c\u308b"
        try:
            # XXX - Note - should be using TESTFN_ENCODING here - but for
            # Windows, "mbcs" currently always operates as if in
            # errors=ignore' mode - hence we get '?' characters rather than
            # the exception.  'Latin1' operates as we expect - ie, fails.
            # See [ 850997 ] mbcs encoding ignores errors
            TESTFN_UNICODE_UNENCODEABLE.encode("Latin1")
        except UnicodeEncodeError:
            pass
        else:
            print('WARNING: The filename %r CAN be encoded by the filesystem.  ' \
            'Unicode filename tests may not be effective' \
            % TESTFN_UNICODE_UNENCODEABLE)

# Make sure we can write to TESTFN, try in /tmp if we can't
fp = None
try:
    fp = open(TESTFN, 'w+')
except IOError:
    TMP_TESTFN = os.path.join('/tmp', TESTFN)
    try:
        fp = open(TMP_TESTFN, 'w+')
        TESTFN = TMP_TESTFN
        del TMP_TESTFN
    except IOError:
        print(('WARNING: tests will fail, unable to write to: %s or %s' %
                (TESTFN, TMP_TESTFN)))
if fp is not None:
    fp.close()
    unlink(TESTFN)
del fp

def findfile(file, here=__file__):
    """Try to find a file on sys.path and the working directory.  If it is not
    found the argument passed to the function is returned (this does not
    necessarily signal failure; could still be the legitimate path)."""
    if os.path.isabs(file):
        return file
    path = sys.path
    path = [os.path.dirname(here)] + path
    for dn in path:
        fn = os.path.join(dn, file)
        if os.path.exists(fn): return fn
    return file

def verify(condition, reason='test failed'):
    """Verify that condition is true. If not, raise TestFailed.

       The optional argument reason can be given to provide
       a better error text.
    """

    if not condition:
        raise TestFailed(reason)

def vereq(a, b):
    """Raise TestFailed if a == b is false.

    This is better than verify(a == b) because, in case of failure, the
    error message incorporates repr(a) and repr(b) so you can see the
    inputs.

    Note that "not (a == b)" isn't necessarily the same as "a != b"; the
    former is tested.
    """

    if not (a == b):
        raise TestFailed("%r == %r" % (a, b))

def sortdict(dict):
    "Like repr(dict), but in sorted order."
    items = sorted(dict.items())
    reprpairs = ["%r: %r" % pair for pair in items]
    withcommas = ", ".join(reprpairs)
    return "{%s}" % withcommas

def check_syntax_error(testcase, statement):
    try:
        compile(statement, '<test string>', 'exec')
    except SyntaxError:
        pass
    else:
        testcase.fail('Missing SyntaxError: "%s"' % statement)

def open_urlresource(url, *args, **kw):
    import urllib, urlparse

    requires('urlfetch')
    filename = urlparse.urlparse(url)[2].split('/')[-1] # '/': it's URL!

    for path in [os.path.curdir, os.path.pardir]:
        fn = os.path.join(path, filename)
        if os.path.exists(fn):
            return open(fn, *args, **kw)

    print('\tfetching %s ...' % url, file=get_original_stdout())
    fn, _ = urllib.urlretrieve(url, filename)
    return open(fn, *args, **kw)


class WarningMessage(object):
    "Holds the result of the latest showwarning() call"
    def __init__(self):
        self.message = None
        self.category = None
        self.filename = None
        self.lineno = None

    def _showwarning(self, message, category, filename, lineno, file=None):
        self.message = message
        self.category = category
        self.filename = filename
        self.lineno = lineno

@contextlib.contextmanager
def catch_warning():
    """
    Guard the warnings filter from being permanently changed and record the
    data of the last warning that has been issued.

    Use like this:

        with catch_warning() as w:
            warnings.warn("foo")
            assert str(w.message) == "foo"
    """
    warning = WarningMessage()
    original_filters = warnings.filters[:]
    original_showwarning = warnings.showwarning
    warnings.showwarning = warning._showwarning
    try:
        yield warning
    finally:
        warnings.showwarning = original_showwarning
        warnings.filters = original_filters

class EnvironmentVarGuard(object):

    """Class to help protect the environment variable properly.  Can be used as
    a context manager."""

    def __init__(self):
        self._environ = os.environ
        self._unset = set()
        self._reset = dict()

    def set(self, envvar, value):
        if envvar not in self._environ:
            self._unset.add(envvar)
        else:
            self._reset[envvar] = self._environ[envvar]
        self._environ[envvar] = value

    def unset(self, envvar):
        if envvar in self._environ:
            self._reset[envvar] = self._environ[envvar]
            del self._environ[envvar]

    def __enter__(self):
        return self

    def __exit__(self, *ignore_exc):
        for envvar, value in self._reset.items():
            self._environ[envvar] = value
        for unset in self._unset:
            del self._environ[unset]

class TransientResource(object):

    """Raise ResourceDenied if an exception is raised while the context manager
    is in effect that matches the specified exception and attributes."""

    def __init__(self, exc, **kwargs):
        self.exc = exc
        self.attrs = kwargs

    def __enter__(self):
        return self

    def __exit__(self, type_=None, value=None, traceback=None):
        """If type_ is a subclass of self.exc and value has attributes matching
        self.attrs, raise ResourceDenied.  Otherwise let the exception
        propagate (if any)."""
        if type_ is not None and issubclass(self.exc, type_):
            for attr, attr_value in self.attrs.items():
                if not hasattr(value, attr):
                    break
                if getattr(value, attr) != attr_value:
                    break
            else:
                raise ResourceDenied("an optional resource is not available")


def transient_internet():
    """Return a context manager that raises ResourceDenied when various issues
    with the Internet connection manifest themselves as exceptions."""
    time_out = TransientResource(IOError, errno=errno.ETIMEDOUT)
    socket_peer_reset = TransientResource(socket.error, errno=errno.ECONNRESET)
    ioerror_peer_reset = TransientResource(IOError, errno=errno.ECONNRESET)
    return contextlib.nested(time_out, socket_peer_reset, ioerror_peer_reset)


@contextlib.contextmanager
def captured_stdout():
    """Run the with statement body using a StringIO object as sys.stdout.
    Example use::

       with captured_stdout() as s:
           print "hello"
       assert s.getvalue() == "hello"
    """
    import io
    orig_stdout = sys.stdout
    sys.stdout = io.StringIO()
    yield sys.stdout
    sys.stdout = orig_stdout


#=======================================================================
# Decorator for running a function in a different locale, correctly resetting
# it afterwards.

def run_with_locale(catstr, *locales):
    def decorator(func):
        def inner(*args, **kwds):
            try:
                import locale
                category = getattr(locale, catstr)
                orig_locale = locale.setlocale(category)
            except AttributeError:
                # if the test author gives us an invalid category string
                raise
            except:
                # cannot retrieve original locale, so do nothing
                locale = orig_locale = None
            else:
                for loc in locales:
                    try:
                        locale.setlocale(category, loc)
                        break
                    except:
                        pass

            # now run the function, resetting the locale on exceptions
            try:
                return func(*args, **kwds)
            finally:
                if locale and orig_locale:
                    locale.setlocale(category, orig_locale)
        inner.__name__ = func.__name__
        inner.__doc__ = func.__doc__
        return inner
    return decorator

#=======================================================================
# Big-memory-test support. Separate from 'resources' because memory use should be configurable.

# Some handy shorthands. Note that these are used for byte-limits as well
# as size-limits, in the various bigmem tests
_1M = 1024*1024
_1G = 1024 * _1M
_2G = 2 * _1G

MAX_Py_ssize_t = sys.maxsize

def set_memlimit(limit):
    import re
    global max_memuse
    sizes = {
        'k': 1024,
        'm': _1M,
        'g': _1G,
        't': 1024*_1G,
    }
    m = re.match(r'(\d+(\.\d+)?) (K|M|G|T)b?$', limit,
                 re.IGNORECASE | re.VERBOSE)
    if m is None:
        raise ValueError('Invalid memory limit %r' % (limit,))
    memlimit = int(float(m.group(1)) * sizes[m.group(3).lower()])
    if memlimit > MAX_Py_ssize_t:
        memlimit = MAX_Py_ssize_t
    if memlimit < _2G - 1:
        raise ValueError('Memory limit %r too low to be useful' % (limit,))
    max_memuse = memlimit

def bigmemtest(minsize, memuse, overhead=5*_1M):
    """Decorator for bigmem tests.

    'minsize' is the minimum useful size for the test (in arbitrary,
    test-interpreted units.) 'memuse' is the number of 'bytes per size' for
    the test, or a good estimate of it. 'overhead' specifies fixed overhead,
    independant of the testsize, and defaults to 5Mb.

    The decorator tries to guess a good value for 'size' and passes it to
    the decorated test function. If minsize * memuse is more than the
    allowed memory use (as defined by max_memuse), the test is skipped.
    Otherwise, minsize is adjusted upward to use up to max_memuse.
    """
    def decorator(f):
        def wrapper(self):
            if not max_memuse:
                # If max_memuse is 0 (the default),
                # we still want to run the tests with size set to a few kb,
                # to make sure they work. We still want to avoid using
                # too much memory, though, but we do that noisily.
                maxsize = 5147
                self.failIf(maxsize * memuse + overhead > 20 * _1M)
            else:
                maxsize = int((max_memuse - overhead) / memuse)
                if maxsize < minsize:
                    # Really ought to print 'test skipped' or something
                    if verbose:
                        sys.stderr.write("Skipping %s because of memory "
                                         "constraint\n" % (f.__name__,))
                    return
                # Try to keep some breathing room in memory use
                maxsize = max(maxsize - 50 * _1M, minsize)
            return f(self, maxsize)
        wrapper.minsize = minsize
        wrapper.memuse = memuse
        wrapper.overhead = overhead
        return wrapper
    return decorator

def bigaddrspacetest(f):
    """Decorator for tests that fill the address space."""
    def wrapper(self):
        if max_memuse < MAX_Py_ssize_t:
            if verbose:
                sys.stderr.write("Skipping %s because of memory "
                                 "constraint\n" % (f.__name__,))
        else:
            return f(self)
    return wrapper

#=======================================================================
# unittest integration.

class BasicTestRunner:
    def run(self, test):
        result = unittest.TestResult()
        test(result)
        return result


def _run_suite(suite):
    """Run tests from a unittest.TestSuite-derived class."""
    if verbose:
        runner = unittest.TextTestRunner(sys.stdout, verbosity=2)
    else:
        runner = BasicTestRunner()

    result = runner.run(suite)
    if not result.wasSuccessful():
        if len(result.errors) == 1 and not result.failures:
            err = result.errors[0][1]
        elif len(result.failures) == 1 and not result.errors:
            err = result.failures[0][1]
        else:
            msg = "errors occurred; run in verbose mode for details"
            raise TestFailed(msg)
        raise TestFailed(err)


def run_unittest(*classes):
    """Run tests from unittest.TestCase-derived classes."""
    valid_types = (unittest.TestSuite, unittest.TestCase)
    suite = unittest.TestSuite()
    for cls in classes:
        if isinstance(cls, basestring):
            if cls in sys.modules:
                suite.addTest(unittest.findTestCases(sys.modules[cls]))
            else:
                raise ValueError("str arguments must be keys in sys.modules")
        elif isinstance(cls, valid_types):
            suite.addTest(cls)
        else:
            suite.addTest(unittest.makeSuite(cls))
    _run_suite(suite)


#=======================================================================
# doctest driver.

def run_doctest(module, verbosity=None):
    """Run doctest on the given module.  Return (#failures, #tests).

    If optional argument verbosity is not specified (or is None), pass
    test_support's belief about verbosity on to doctest.  Else doctest's
    usual behavior is used (it searches sys.argv for -v).
    """

    import doctest

    if verbosity is None:
        verbosity = verbose
    else:
        verbosity = None

    # Direct doctest output (normally just errors) to real stdout; doctest
    # output shouldn't be compared by regrtest.
    save_stdout = sys.stdout
    sys.stdout = get_original_stdout()
    try:
        f, t = doctest.testmod(module, verbose=verbosity)
        if f:
            raise TestFailed("%d of %d doctests failed" % (f, t))
    finally:
        sys.stdout = save_stdout
    if verbose:
        print('doctest (%s) ... %d tests with zero failures' % (module.__name__, t))
    return f, t

#=======================================================================
# Threading support to prevent reporting refleaks when running regrtest.py -R

def threading_setup():
    import threading
    return len(threading._active), len(threading._limbo)

def threading_cleanup(num_active, num_limbo):
    import threading
    import time

    _MAX_COUNT = 10
    count = 0
    while len(threading._active) != num_active and count < _MAX_COUNT:
        count += 1
        time.sleep(0.1)

    count = 0
    while len(threading._limbo) != num_limbo and count < _MAX_COUNT:
        count += 1
        time.sleep(0.1)

def reap_children():
    """Use this function at the end of test_main() whenever sub-processes
    are started.  This will help ensure that no extra children (zombies)
    stick around to hog resources and create problems when looking
    for refleaks.
    """

    # Reap all our dead child processes so we don't leave zombies around.
    # These hog resources and might be causing some of the buildbots to die.
    if hasattr(os, 'waitpid'):
        any_process = -1
        while True:
            try:
                # This will raise an exception on Windows.  That's ok.
                pid, status = os.waitpid(any_process, os.WNOHANG)
                if pid == 0:
                    break
            except:
                break