108 lines
3.9 KiB
Python
108 lines
3.9 KiB
Python
# From scikit-image: https://github.com/scikit-image/scikit-image/blob/c2f8c4ab123ebe5f7b827bc495625a32bb225c10/skimage/_shared/_warnings.py
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# Licensed under modified BSD license
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__all__ = ['all_warnings', 'expected_warnings']
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from contextlib import contextmanager
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import sys
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import warnings
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import inspect
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import re
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@contextmanager
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def all_warnings():
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"""
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Context for use in testing to ensure that all warnings are raised.
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Examples
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--------
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>>> import warnings
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>>> def foo():
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... warnings.warn(RuntimeWarning("bar"))
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We raise the warning once, while the warning filter is set to "once".
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Hereafter, the warning is invisible, even with custom filters:
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>>> with warnings.catch_warnings():
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... warnings.simplefilter('once')
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... foo()
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We can now run ``foo()`` without a warning being raised:
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>>> from numpy.testing import assert_warns
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>>> foo()
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To catch the warning, we call in the help of ``all_warnings``:
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>>> with all_warnings():
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... assert_warns(RuntimeWarning, foo)
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"""
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# Whenever a warning is triggered, Python adds a __warningregistry__
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# member to the *calling* module. The exercize here is to find
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# and eradicate all those breadcrumbs that were left lying around.
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#
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# We proceed by first searching all parent calling frames and explicitly
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# clearing their warning registries (necessary for the doctests above to
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# pass). Then, we search for all submodules of skimage and clear theirs
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# as well (necessary for the skimage test suite to pass).
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frame = inspect.currentframe()
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if frame:
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for f in inspect.getouterframes(frame):
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f[0].f_locals['__warningregistry__'] = {}
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del frame
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for mod_name, mod in list(sys.modules.items()):
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if 'six.moves' in mod_name:
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continue
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try:
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mod.__warningregistry__.clear()
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except AttributeError:
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pass
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with warnings.catch_warnings(record=True) as w:
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warnings.simplefilter("always")
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yield w
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@contextmanager
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def expected_warnings(matching):
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"""Context for use in testing to catch known warnings matching regexes
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Parameters
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----------
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matching : list of strings or compiled regexes
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Regexes for the desired warning to catch
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Examples
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--------
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>>> from skimage import data, img_as_ubyte, img_as_float
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>>> with expected_warnings(['precision loss']):
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... d = img_as_ubyte(img_as_float(data.coins()))
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Notes
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-----
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Uses `all_warnings` to ensure all warnings are raised.
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Upon exiting, it checks the recorded warnings for the desired matching
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pattern(s).
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Raises a ValueError if any match was not found or an unexpected
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warning was raised.
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Allows for three types of behaviors: "and", "or", and "optional" matches.
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This is done to accomodate different build enviroments or loop conditions
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that may produce different warnings. The behaviors can be combined.
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If you pass multiple patterns, you get an orderless "and", where all of the
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warnings must be raised.
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If you use the "|" operator in a pattern, you can catch one of several warnings.
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Finally, you can use "|\A\Z" in a pattern to signify it as optional.
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"""
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with all_warnings() as w:
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# enter context
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yield w
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# exited user context, check the recorded warnings
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remaining = [m for m in matching if not '\A\Z' in m.split('|')]
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for warn in w:
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found = False
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for match in matching:
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if re.search(match, str(warn.message)) is not None:
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found = True
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if match in remaining:
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remaining.remove(match)
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if not found:
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raise ValueError('Unexpected warning: %s' % str(warn.message))
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if len(remaining) > 0:
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msg = 'No warning raised matching:\n%s' % '\n'.join(remaining)
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raise ValueError(msg)
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