Function expected_warnings

tests/_warnings.py:70–115

r"""Context for use in testing to catch known warnings matching regexes Parameters ---------- matching : list of strings or compiled regexes Regexes for the desired warning to catch Examples -------- >>> from skimage import data, img_as_ubyte, img_as_float # doctes

(matching)

@contextmanager
def expected_warnings(matching):
    r"""Context for use in testing to catch known warnings matching regexes

    Parameters
    ----------
    matching : list of strings or compiled regexes
        Regexes for the desired warning to catch

    Examples
    --------
    >>> from skimage import data, img_as_ubyte, img_as_float  # doctest: +SKIP
    >>> with expected_warnings(["precision loss"]):           # doctest: +SKIP
    ...     d = img_as_ubyte(img_as_float(data.coins()))      # doctest: +SKIP

    Notes
    -----
    Uses `all_warnings` to ensure all warnings are raised.
    Upon exiting, it checks the recorded warnings for the desired matching
    pattern(s).
    Raises a ValueError if any match was not found or an unexpected
    warning was raised.
    Allows for three types of behaviors: "and", "or", and "optional" matches.
    This is done to accommodate different build environments or loop conditions
    that may produce different warnings.  The behaviors can be combined.
    If you pass multiple patterns, you get an orderless "and", where all of the
    warnings must be raised.
    If you use the "|" operator in a pattern, you can catch one of several warnings.
    Finally, you can use "|\A\Z" in a pattern to signify it as optional.
    """
    with all_warnings() as w:
        # enter context
        yield w
        # exited user context, check the recorded warnings
        remaining = [m for m in matching if r"\A\Z" not in m.split("|")]
        for warn in w:
            found = False
            for match in matching:
                if re.search(match, str(warn.message)) is not None:
                    found = True
                    if match in remaining:
                        remaining.remove(match)
            if not found:
                raise ValueError("Unexpected warning: %s" % str(warn.message))
        if len(remaining) > 0:
            msg = "No warning raised matching:\n%s" % "\n".join(remaining)
            raise ValueError(msg)