testing.py

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#!/usr/bin/env python
"""Support classes for automated testing.

* `AsyncTestCase` and `AsyncHTTPTestCase`:  Subclasses of unittest.TestCase
  with additional support for testing asynchronous (`.IOLoop` based) code.

* `ExpectLog` and `LogTrapTestCase`: Make test logs less spammy.

* `main()`: A simple test runner (wrapper around unittest.main()) with support
  for the tornado.autoreload module to rerun the tests when code changes.
"""

from __future__ import absolute_import, division, print_function, with_statement

try:
    from tornado import gen
    from tornado.httpclient import AsyncHTTPClient
    from tornado.httpserver import HTTPServer
    from tornado.simple_httpclient import SimpleAsyncHTTPClient
    from tornado.ioloop import IOLoop, TimeoutError
    from tornado import netutil
except ImportError:
    # These modules are not importable on app engine.  Parts of this module
    # won't work, but e.g. LogTrapTestCase and main() will.
    AsyncHTTPClient = None
    gen = None
    HTTPServer = None
    IOLoop = None
    netutil = None
    SimpleAsyncHTTPClient = None
from tornado.log import gen_log
from tornado.stack_context import ExceptionStackContext
from tornado.util import raise_exc_info, basestring_type
import functools
import logging
import os
import re
import signal
import socket
import sys
import types

try:
    from cStringIO import StringIO  # py2
except ImportError:
    from io import StringIO  # py3

# Tornado's own test suite requires the updated unittest module
# (either py27+ or unittest2) so tornado.test.util enforces
# this requirement, but for other users of tornado.testing we want
# to allow the older version if unitest2 is not available.
if sys.version_info >= (3,):
    # On python 3, mixing unittest2 and unittest (including doctest)
    # doesn't seem to work, so always use unittest.
    import unittest
else:
    # On python 2, prefer unittest2 when available.
    try:
        import unittest2 as unittest
    except ImportError:
        import unittest

_next_port = 10000


def get_unused_port():
    """Returns a (hopefully) unused port number.

    This function does not guarantee that the port it returns is available,
    only that a series of get_unused_port calls in a single process return
    distinct ports.

    .. deprecated::
       Use bind_unused_port instead, which is guaranteed to find an unused port.
    """
    global _next_port
    port = _next_port
    _next_port = _next_port + 1
    return port


def bind_unused_port():
    """Binds a server socket to an available port on localhost.

    Returns a tuple (socket, port).
    """
    [sock] = netutil.bind_sockets(None, 'localhost', family=socket.AF_INET)
    port = sock.getsockname()[1]
    return sock, port


def get_async_test_timeout():
    """Get the global timeout setting for async tests.

    Returns a float, the timeout in seconds.

    .. versionadded:: 3.1
    """
    try:
        return float(os.environ.get('ASYNC_TEST_TIMEOUT'))
    except (ValueError, TypeError):
        return 5


class _TestMethodWrapper(object):
    """Wraps a test method to raise an error if it returns a value.

    This is mainly used to detect undecorated generators (if a test
    method yields it must use a decorator to consume the generator),
    but will also detect other kinds of return values (these are not
    necessarily errors, but we alert anyway since there is no good
    reason to return a value from a test.
    """
    def __init__(self, orig_method):
        self.orig_method = orig_method

    def __call__(self, *args, **kwargs):
        result = self.orig_method(*args, **kwargs)
        if isinstance(result, types.GeneratorType):
            raise TypeError("Generator test methods should be decorated with "
                            "tornado.testing.gen_test")
        elif result is not None:
            raise ValueError("Return value from test method ignored: %r" %
                             result)

    def __getattr__(self, name):
        """Proxy all unknown attributes to the original method.

        This is important for some of the decorators in the `unittest`
        module, such as `unittest.skipIf`.
        """
        return getattr(self.orig_method, name)


class AsyncTestCase(unittest.TestCase):
    """`~unittest.TestCase` subclass for testing `.IOLoop`-based
    asynchronous code.

    The unittest framework is synchronous, so the test must be
    complete by the time the test method returns.  This means that
    asynchronous code cannot be used in quite the same way as usual.
    To write test functions that use the same ``yield``-based patterns
    used with the `tornado.gen` module, decorate your test methods
    with `tornado.testing.gen_test` instead of
    `tornado.gen.coroutine`.  This class also provides the `stop()`
    and `wait()` methods for a more manual style of testing.  The test
    method itself must call ``self.wait()``, and asynchronous
    callbacks should call ``self.stop()`` to signal completion.

    By default, a new `.IOLoop` is constructed for each test and is available
    as ``self.io_loop``.  This `.IOLoop` should be used in the construction of
    HTTP clients/servers, etc.  If the code being tested requires a
    global `.IOLoop`, subclasses should override `get_new_ioloop` to return it.

    The `.IOLoop`'s ``start`` and ``stop`` methods should not be
    called directly.  Instead, use `self.stop <stop>` and `self.wait
    <wait>`.  Arguments passed to ``self.stop`` are returned from
    ``self.wait``.  It is possible to have multiple ``wait``/``stop``
    cycles in the same test.

    Example::

        # This test uses coroutine style.
        class MyTestCase(AsyncTestCase):
            @tornado.testing.gen_test
            def test_http_fetch(self):
                client = AsyncHTTPClient(self.io_loop)
                response = yield client.fetch("http://www.tornadoweb.org")
                # Test contents of response
                self.assertIn("FriendFeed", response.body)

        # This test uses argument passing between self.stop and self.wait.
        class MyTestCase2(AsyncTestCase):
            def test_http_fetch(self):
                client = AsyncHTTPClient(self.io_loop)
                client.fetch("http://www.tornadoweb.org/", self.stop)
                response = self.wait()
                # Test contents of response
                self.assertIn("FriendFeed", response.body)

        # This test uses an explicit callback-based style.
        class MyTestCase3(AsyncTestCase):
            def test_http_fetch(self):
                client = AsyncHTTPClient(self.io_loop)
                client.fetch("http://www.tornadoweb.org/", self.handle_fetch)
                self.wait()

            def handle_fetch(self, response):
                # Test contents of response (failures and exceptions here
                # will cause self.wait() to throw an exception and end the
                # test).
                # Exceptions thrown here are magically propagated to
                # self.wait() in test_http_fetch() via stack_context.
                self.assertIn("FriendFeed", response.body)
                self.stop()
    """
    def __init__(self, methodName='runTest', **kwargs):
        super(AsyncTestCase, self).__init__(methodName, **kwargs)
        self.__stopped = False
        self.__running = False
        self.__failure = None
        self.__stop_args = None
        self.__timeout = None

        # It's easy to forget the @gen_test decorator, but if you do
        # the test will silently be ignored because nothing will consume
        # the generator.  Replace the test method with a wrapper that will
        # make sure it's not an undecorated generator.
        setattr(self, methodName, _TestMethodWrapper(getattr(self, methodName)))

    def setUp(self):
        super(AsyncTestCase, self).setUp()
        self.io_loop = self.get_new_ioloop()
        self.io_loop.make_current()

    def tearDown(self):
        self.io_loop.clear_current()
        if (not IOLoop.initialized() or
                self.io_loop is not IOLoop.instance()):
            # Try to clean up any file descriptors left open in the ioloop.
            # This avoids leaks, especially when tests are run repeatedly
            # in the same process with autoreload (because curl does not
            # set FD_CLOEXEC on its file descriptors)
            self.io_loop.close(all_fds=True)
        super(AsyncTestCase, self).tearDown()
        # In case an exception escaped or the StackContext caught an exception
        # when there wasn't a wait() to re-raise it, do so here.
        # This is our last chance to raise an exception in a way that the
        # unittest machinery understands.
        self.__rethrow()

    def get_new_ioloop(self):
        """Creates a new `.IOLoop` for this test.  May be overridden in
        subclasses for tests that require a specific `.IOLoop` (usually
        the singleton `.IOLoop.instance()`).
        """
        return IOLoop()

    def _handle_exception(self, typ, value, tb):
        self.__failure = (typ, value, tb)
        self.stop()
        return True

    def __rethrow(self):
        if self.__failure is not None:
            failure = self.__failure
            self.__failure = None
            raise_exc_info(failure)

    def run(self, result=None):
        with ExceptionStackContext(self._handle_exception):
            super(AsyncTestCase, self).run(result)
        # As a last resort, if an exception escaped super.run() and wasn't
        # re-raised in tearDown, raise it here.  This will cause the
        # unittest run to fail messily, but that's better than silently
        # ignoring an error.
        self.__rethrow()

    def stop(self, _arg=None, **kwargs):
        """Stops the `.IOLoop`, causing one pending (or future) call to `wait()`
        to return.

        Keyword arguments or a single positional argument passed to `stop()` are
        saved and will be returned by `wait()`.
        """
        assert _arg is None or not kwargs
        self.__stop_args = kwargs or _arg
        if self.__running:
            self.io_loop.stop()
            self.__running = False
        self.__stopped = True

    def wait(self, condition=None, timeout=None):
        """Runs the `.IOLoop` until stop is called or timeout has passed.

        In the event of a timeout, an exception will be thrown. The
        default timeout is 5 seconds; it may be overridden with a
        ``timeout`` keyword argument or globally with the
        ``ASYNC_TEST_TIMEOUT`` environment variable.

        If ``condition`` is not None, the `.IOLoop` will be restarted
        after `stop()` until ``condition()`` returns true.

        .. versionchanged:: 3.1
           Added the ``ASYNC_TEST_TIMEOUT`` environment variable.
        """
        if timeout is None:
            timeout = get_async_test_timeout()

        if not self.__stopped:
            if timeout:
                def timeout_func():
                    try:
                        raise self.failureException(
                            'Async operation timed out after %s seconds' %
                            timeout)
                    except Exception:
                        self.__failure = sys.exc_info()
                    self.stop()
                self.__timeout = self.io_loop.add_timeout(self.io_loop.time() + timeout, timeout_func)
            while True:
                self.__running = True
                self.io_loop.start()
                if (self.__failure is not None or
                        condition is None or condition()):
                    break
            if self.__timeout is not None:
                self.io_loop.remove_timeout(self.__timeout)
                self.__timeout = None
        assert self.__stopped
        self.__stopped = False
        self.__rethrow()
        result = self.__stop_args
        self.__stop_args = None
        return result


class AsyncHTTPTestCase(AsyncTestCase):
    """A test case that starts up an HTTP server.

    Subclasses must override `get_app()`, which returns the
    `tornado.web.Application` (or other `.HTTPServer` callback) to be tested.
    Tests will typically use the provided ``self.http_client`` to fetch
    URLs from this server.

    Example::

        class MyHTTPTest(AsyncHTTPTestCase):
            def get_app(self):
                return Application([('/', MyHandler)...])

            def test_homepage(self):
                # The following two lines are equivalent to
                #   response = self.fetch('/')
                # but are shown in full here to demonstrate explicit use
                # of self.stop and self.wait.
                self.http_client.fetch(self.get_url('/'), self.stop)
                response = self.wait()
                # test contents of response
    """
    def setUp(self):
        super(AsyncHTTPTestCase, self).setUp()
        sock, port = bind_unused_port()
        self.__port = port

        self.http_client = self.get_http_client()
        self._app = self.get_app()
        self.http_server = self.get_http_server()
        self.http_server.add_sockets([sock])

    def get_http_client(self):
        return AsyncHTTPClient(io_loop=self.io_loop)

    def get_http_server(self):
        return HTTPServer(self._app, io_loop=self.io_loop,
                          **self.get_httpserver_options())

    def get_app(self):
        """Should be overridden by subclasses to return a
        `tornado.web.Application` or other `.HTTPServer` callback.
        """
        raise NotImplementedError()

    def fetch(self, path, **kwargs):
        """Convenience method to synchronously fetch a url.

        The given path will be appended to the local server's host and
        port.  Any additional kwargs will be passed directly to
        `.AsyncHTTPClient.fetch` (and so could be used to pass
        ``method="POST"``, ``body="..."``, etc).
        """
        self.http_client.fetch(self.get_url(path), self.stop, **kwargs)
        return self.wait()

    def get_httpserver_options(self):
        """May be overridden by subclasses to return additional
        keyword arguments for the server.
        """
        return {}

    def get_http_port(self):
        """Returns the port used by the server.

        A new port is chosen for each test.
        """
        return self.__port

    def get_protocol(self):
        return 'http'

    def get_url(self, path):
        """Returns an absolute url for the given path on the test server."""
        return '%s://localhost:%s%s' % (self.get_protocol(),
                                        self.get_http_port(), path)

    def tearDown(self):
        self.http_server.stop()
        self.io_loop.run_sync(self.http_server.close_all_connections)
        if (not IOLoop.initialized() or
                self.http_client.io_loop is not IOLoop.instance()):
            self.http_client.close()
        super(AsyncHTTPTestCase, self).tearDown()


class AsyncHTTPSTestCase(AsyncHTTPTestCase):
    """A test case that starts an HTTPS server.

    Interface is generally the same as `AsyncHTTPTestCase`.
    """
    def get_http_client(self):
        # Some versions of libcurl have deadlock bugs with ssl,
        # so always run these tests with SimpleAsyncHTTPClient.
        return SimpleAsyncHTTPClient(io_loop=self.io_loop, force_instance=True,
                                     defaults=dict(validate_cert=False))

    def get_httpserver_options(self):
        return dict(ssl_options=self.get_ssl_options())

    def get_ssl_options(self):
        """May be overridden by subclasses to select SSL options.

        By default includes a self-signed testing certificate.
        """
        # Testing keys were generated with:
        # openssl req -new -keyout tornado/test/test.key -out tornado/test/test.crt -nodes -days 3650 -x509
        module_dir = os.path.dirname(__file__)
        return dict(
            certfile=os.path.join(module_dir, 'test', 'test.crt'),
            keyfile=os.path.join(module_dir, 'test', 'test.key'))

    def get_protocol(self):
        return 'https'


def gen_test(func=None, timeout=None):
    """Testing equivalent of ``@gen.coroutine``, to be applied to test methods.

    ``@gen.coroutine`` cannot be used on tests because the `.IOLoop` is not
    already running.  ``@gen_test`` should be applied to test methods
    on subclasses of `AsyncTestCase`.

    Example::

        class MyTest(AsyncHTTPTestCase):
            @gen_test
            def test_something(self):
                response = yield gen.Task(self.fetch('/'))

    By default, ``@gen_test`` times out after 5 seconds. The timeout may be
    overridden globally with the ``ASYNC_TEST_TIMEOUT`` environment variable,
    or for each test with the ``timeout`` keyword argument::

        class MyTest(AsyncHTTPTestCase):
            @gen_test(timeout=10)
            def test_something_slow(self):
                response = yield gen.Task(self.fetch('/'))

    .. versionadded:: 3.1
       The ``timeout`` argument and ``ASYNC_TEST_TIMEOUT`` environment
       variable.

    .. versionchanged:: 4.0
       The wrapper now passes along ``*args, **kwargs`` so it can be used
       on functions with arguments.
    """
    if timeout is None:
        timeout = get_async_test_timeout()

    def wrap(f):
        # Stack up several decorators to allow us to access the generator
        # object itself.  In the innermost wrapper, we capture the generator
        # and save it in an attribute of self.  Next, we run the wrapped
        # function through @gen.coroutine.  Finally, the coroutine is
        # wrapped again to make it synchronous with run_sync.
        #
        # This is a good case study arguing for either some sort of
        # extensibility in the gen decorators or cancellation support.
        @functools.wraps(f)
        def pre_coroutine(self, *args, **kwargs):
            result = f(self, *args, **kwargs)
            if isinstance(result, types.GeneratorType):
                self._test_generator = result
            else:
                self._test_generator = None
            return result

        coro = gen.coroutine(pre_coroutine)

        @functools.wraps(coro)
        def post_coroutine(self, *args, **kwargs):
            try:
                return self.io_loop.run_sync(
                    functools.partial(coro, self, *args, **kwargs),
                    timeout=timeout)
            except TimeoutError as e:
                # run_sync raises an error with an unhelpful traceback.
                # If we throw it back into the generator the stack trace
                # will be replaced by the point where the test is stopped.
                self._test_generator.throw(e)
                # In case the test contains an overly broad except clause,
                # we may get back here.  In this case re-raise the original
                # exception, which is better than nothing.
                raise
        return post_coroutine

    if func is not None:
        # Used like:
        #     @gen_test
        #     def f(self):
        #         pass
        return wrap(func)
    else:
        # Used like @gen_test(timeout=10)
        return wrap


# Without this attribute, nosetests will try to run gen_test as a test
# anywhere it is imported.
gen_test.__test__ = False


class LogTrapTestCase(unittest.TestCase):
    """A test case that captures and discards all logging output
    if the test passes.

    Some libraries can produce a lot of logging output even when
    the test succeeds, so this class can be useful to minimize the noise.
    Simply use it as a base class for your test case.  It is safe to combine
    with AsyncTestCase via multiple inheritance
    (``class MyTestCase(AsyncHTTPTestCase, LogTrapTestCase):``)

    This class assumes that only one log handler is configured and
    that it is a `~logging.StreamHandler`.  This is true for both
    `logging.basicConfig` and the "pretty logging" configured by
    `tornado.options`.  It is not compatible with other log buffering
    mechanisms, such as those provided by some test runners.
    """
    def run(self, result=None):
        logger = logging.getLogger()
        if not logger.handlers:
            logging.basicConfig()
        handler = logger.handlers[0]
        if (len(logger.handlers) > 1 or
                not isinstance(handler, logging.StreamHandler)):
            # Logging has been configured in a way we don't recognize,
            # so just leave it alone.
            super(LogTrapTestCase, self).run(result)
            return
        old_stream = handler.stream
        try:
            handler.stream = StringIO()
            gen_log.info("RUNNING TEST: " + str(self))
            old_error_count = len(result.failures) + len(result.errors)
            super(LogTrapTestCase, self).run(result)
            new_error_count = len(result.failures) + len(result.errors)
            if new_error_count != old_error_count:
                old_stream.write(handler.stream.getvalue())
        finally:
            handler.stream = old_stream


class ExpectLog(logging.Filter):
    """Context manager to capture and suppress expected log output.

    Useful to make tests of error conditions less noisy, while still
    leaving unexpected log entries visible.  *Not thread safe.*

    Usage::

        with ExpectLog('tornado.application', "Uncaught exception"):
            error_response = self.fetch("/some_page")
    """
    def __init__(self, logger, regex, required=True):
        """Constructs an ExpectLog context manager.

        :param logger: Logger object (or name of logger) to watch.  Pass
            an empty string to watch the root logger.
        :param regex: Regular expression to match.  Any log entries on
            the specified logger that match this regex will be suppressed.
        :param required: If true, an exeption will be raised if the end of
            the ``with`` statement is reached without matching any log entries.
        """
        if isinstance(logger, basestring_type):
            logger = logging.getLogger(logger)
        self.logger = logger
        self.regex = re.compile(regex)
        self.required = required
        self.matched = False

    def filter(self, record):
        message = record.getMessage()
        if self.regex.match(message):
            self.matched = True
            return False
        return True

    def __enter__(self):
        self.logger.addFilter(self)

    def __exit__(self, typ, value, tb):
        self.logger.removeFilter(self)
        if not typ and self.required and not self.matched:
            raise Exception("did not get expected log message")


def main(**kwargs):
    """A simple test runner.

    This test runner is essentially equivalent to `unittest.main` from
    the standard library, but adds support for tornado-style option
    parsing and log formatting.

    The easiest way to run a test is via the command line::

        python -m tornado.testing tornado.test.stack_context_test

    See the standard library unittest module for ways in which tests can
    be specified.

    Projects with many tests may wish to define a test script like
    ``tornado/test/runtests.py``.  This script should define a method
    ``all()`` which returns a test suite and then call
    `tornado.testing.main()`.  Note that even when a test script is
    used, the ``all()`` test suite may be overridden by naming a
    single test on the command line::

        # Runs all tests
        python -m tornado.test.runtests
        # Runs one test
        python -m tornado.test.runtests tornado.test.stack_context_test

    Additional keyword arguments passed through to ``unittest.main()``.
    For example, use ``tornado.testing.main(verbosity=2)``
    to show many test details as they are run.
    See http://docs.python.org/library/unittest.html#unittest.main
    for full argument list.
    """
    from tornado.options import define, options, parse_command_line

    define('exception_on_interrupt', type=bool, default=True,
           help=("If true (default), ctrl-c raises a KeyboardInterrupt "
                 "exception.  This prints a stack trace but cannot interrupt "
                 "certain operations.  If false, the process is more reliably "
                 "killed, but does not print a stack trace."))

    # support the same options as unittest's command-line interface
    define('verbose', type=bool)
    define('quiet', type=bool)
    define('failfast', type=bool)
    define('catch', type=bool)
    define('buffer', type=bool)

    argv = [sys.argv[0]] + parse_command_line(sys.argv)

    if not options.exception_on_interrupt:
        signal.signal(signal.SIGINT, signal.SIG_DFL)

    if options.verbose is not None:
        kwargs['verbosity'] = 2
    if options.quiet is not None:
        kwargs['verbosity'] = 0
    if options.failfast is not None:
        kwargs['failfast'] = True
    if options.catch is not None:
        kwargs['catchbreak'] = True
    if options.buffer is not None:
        kwargs['buffer'] = True

    if __name__ == '__main__' and len(argv) == 1:
        print("No tests specified", file=sys.stderr)
        sys.exit(1)
    try:
        # In order to be able to run tests by their fully-qualified name
        # on the command line without importing all tests here,
        # module must be set to None.  Python 3.2's unittest.main ignores
        # defaultTest if no module is given (it tries to do its own
        # test discovery, which is incompatible with auto2to3), so don't
        # set module if we're not asking for a specific test.
        if len(argv) > 1:
            unittest.main(module=None, argv=argv, **kwargs)
        else:
            unittest.main(defaultTest="all", argv=argv, **kwargs)
    except SystemExit as e:
        if e.code == 0:
            gen_log.info('PASS')
        else:
            gen_log.error('FAIL')
        raise

if __name__ == '__main__':
    main()