environment/lib/python2.7/site-packages/IPython/external/decorators/_decorators.py
def skipif(skip_condition, msg=None):
    """
    Make function raise SkipTest exception if a given condition is true.

    If the condition is a callable, it is used at runtime to dynamically
    make the decision. This is useful for tests that may require costly
    imports, to delay the cost until the test suite is actually executed.

    Parameters
    ----------
    skip_condition : bool or callable
        Flag to determine whether to skip the decorated test.
    msg : str, optional
        Message to give on raising a SkipTest exception. Default is None.

    Returns
    -------
    decorator : function
        Decorator which, when applied to a function, causes SkipTest
        to be raised when `skip_condition` is True, and the function
        to be called normally otherwise.

    Notes
    -----
    The decorator itself is decorated with the ``nose.tools.make_decorator``
    function in order to transmit function name, and various other metadata.

    """

    def skip_decorator(f):
        # Local import to avoid a hard nose dependency and only incur the
        # import time overhead at actual test-time.
        import nose

        # Allow for both boolean or callable skip conditions.
        if callable(skip_condition):
            skip_val = lambda : skip_condition()
        else:
            skip_val = lambda : skip_condition

        def get_msg(func,msg=None):
            """Skip message with information about function being skipped."""
            if msg is None:
                out = 'Test skipped due to test condition'
            else:
                out = '\n'+msg

            return "Skipping test: %s%s" % (func.__name__,out)

        # We need to define *two* skippers because Python doesn't allow both
        # return with value and yield inside the same function.
        def skipper_func(*args, **kwargs):
            """Skipper for normal test functions."""
            if skip_val():
                raise nose.SkipTest(get_msg(f,msg))
            else:
                return f(*args, **kwargs)

        def skipper_gen(*args, **kwargs):
            """Skipper for test generators."""
            if skip_val():
                raise nose.SkipTest(get_msg(f,msg))
            else:
                for x in f(*args, **kwargs):
                    yield x

        # Choose the right skipper to use when building the actual decorator.
        if nose.util.isgenerator(f):
            skipper = skipper_gen
        else:
            skipper = skipper_func

        return nose.tools.make_decorator(f)(skipper)

    return skip_decorator
def skipif(skip_condition, msg=None):
    """
    Make function raise SkipTest exception if a given condition is true.

    If the condition is a callable, it is used at runtime to dynamically
    make the decision. This is useful for tests that may require costly
    imports, to delay the cost until the test suite is actually executed.

    Parameters
    ----------
    skip_condition : bool or callable
        Flag to determine whether to skip the decorated test.
    msg : str, optional
        Message to give on raising a SkipTest exception. Default is None.

    Returns
    -------
    decorator : function
        Decorator which, when applied to a function, causes SkipTest
        to be raised when `skip_condition` is True, and the function
        to be called normally otherwise.

    Notes
    -----
    The decorator itself is decorated with the ``nose.tools.make_decorator``
    function in order to transmit function name, and various other metadata.

    """

    def skip_decorator(f):
        # Local import to avoid a hard nose dependency and only incur the
        # import time overhead at actual test-time.
        import nose

        # Allow for both boolean or callable skip conditions.
        if callable(skip_condition):
            skip_val = lambda : skip_condition()
        else:
            skip_val = lambda : skip_condition

        def get_msg(func,msg=None):
            """Skip message with information about function being skipped."""
            if msg is None:
                out = 'Test skipped due to test condition'
            else:
                out = '\n'+msg

            return "Skipping test: %s%s" % (func.__name__,out)

        # We need to define *two* skippers because Python doesn't allow both
        # return with value and yield inside the same function.
        def skipper_func(*args, **kwargs):
            """Skipper for normal test functions."""
            if skip_val():
                raise nose.SkipTest(get_msg(f,msg))
            else:
                return f(*args, **kwargs)

        def skipper_gen(*args, **kwargs):
            """Skipper for test generators."""
            if skip_val():
                raise nose.SkipTest(get_msg(f,msg))
            else:
                for x in f(*args, **kwargs):
                    yield x

        # Choose the right skipper to use when building the actual decorator.
        if nose.util.isgenerator(f):
            skipper = skipper_gen
        else:
            skipper = skipper_func

        return nose.tools.make_decorator(f)(skipper)

    return skip_decorator
Make function raise SkipTest exception if a given condition is true.

    If the condition is a callable, it is used at runtime to dynamically
    make the decision. This is useful for tests that may require costly
    imports, to delay the cost until the test suite is actually executed.

    Parameters
    ----------
    skip_condition : bool or callable
        Flag to determine whether to skip the decorated test.
    msg : str, optional
        Message to give on raising a SkipTest exception. Default is None.

    Returns
    -------
    decorator : function
        Decorator which, when applied to a function, causes SkipTest
        to be raised when `skip_condition` is True, and the function
        to be called normally otherwise.

    Notes
    -----
    The decorator itself is decorated with the ``nose.tools.make_decorator``
    function in order to transmit function name, and various other metadata.