Class suppress_warnings

numpy/testing/_private/utils.py:2004–2279

Context manager and decorator doing much the same as ``warnings.catch_warnings``. However, it also provides a filter mechanism to work around https://bugs.python.org/issue4180. This bug causes Python before 3.4 to not reliably show warnings again after they have been ignor

class suppress_warnings:
    """
    Context manager and decorator doing much the same as
    ``warnings.catch_warnings``.

    However, it also provides a filter mechanism to work around
    https://bugs.python.org/issue4180.

    This bug causes Python before 3.4 to not reliably show warnings again
    after they have been ignored once (even within catch_warnings). It
    means that no "ignore" filter can be used easily, since following
    tests might need to see the warning. Additionally it allows easier
    specificity for testing warnings and can be nested.

    Parameters
    ----------
    forwarding_rule : str, optional
        One of "always", "once", "module", or "location". Analogous to
        the usual warnings module filter mode, it is useful to reduce
        noise mostly on the outmost level. Unsuppressed and unrecorded
        warnings will be forwarded based on this rule. Defaults to "always".
        "location" is equivalent to the warnings "default", match by exact
        location the warning warning originated from.

    Notes
    -----
    Filters added inside the context manager will be discarded again
    when leaving it. Upon entering all filters defined outside a
    context will be applied automatically.

    When a recording filter is added, matching warnings are stored in the
    ``log`` attribute as well as in the list returned by ``record``.

    If filters are added and the ``module`` keyword is given, the
    warning registry of this module will additionally be cleared when
    applying it, entering the context, or exiting it. This could cause
    warnings to appear a second time after leaving the context if they
    were configured to be printed once (default) and were already
    printed before the context was entered.

    Nesting this context manager will work as expected when the
    forwarding rule is "always" (default). Unfiltered and unrecorded
    warnings will be passed out and be matched by the outer level.
    On the outmost level they will be printed (or caught by another
    warnings context). The forwarding rule argument can modify this
    behaviour.

    Like ``catch_warnings`` this context manager is not threadsafe.

    Examples
    --------

    With a context manager::

        with np.testing.suppress_warnings() as sup:
            sup.filter(DeprecationWarning, "Some text")
            sup.filter(module=np.ma.core)
            log = sup.record(FutureWarning, "Does this occur?")