mirror of
https://github.com/wassname/scikit-image.git
synced 2026-06-30 08:46:14 +08:00
Steven Silvester
2d3ada19e5
Allow for no exceptions to be raised Add some helpful comments Remove doctest skips Remove TODO note Cleanup and skip failing doctest
109 lines
3.3 KiB
Python
109 lines
3.3 KiB
Python
__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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string. Raises a warning if the match was not found or an Unexpected
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warning is found. You can pass an empty regex as on of the matches
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to allow for no matches: "\A\Z".
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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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