146 lines
5 KiB
Python
146 lines
5 KiB
Python
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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 re
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import functools
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import os
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__all__ = ['all_warnings', 'expected_warnings', 'warn']
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# A version of `warnings.warn` with a default stacklevel of 2.
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# functool is used so as not to increase the call stack accidentally
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warn = functools.partial(warnings.warn, stacklevel=2)
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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"), stacklevel=2)
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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() # doctest: +SKIP
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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() # doctest: +SKIP
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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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# _warnings.py is on the critical import path.
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# Since this is a testing only function, we lazy import inspect.
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import inspect
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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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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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r"""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 : None or a list of strings or compiled regexes
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Regexes for the desired warning to catch
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If matching is None, this behaves as a no-op.
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Examples
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--------
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>>> import numpy as np
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>>> image = np.random.randint(0, 2**16, size=(100, 100), dtype=np.uint16)
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>>> # rank filters are slow when bit-depth exceeds 10 bits
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>>> from skimage import filters
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>>> with expected_warnings(['Bad rank filter performance']):
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... median_filtered = filters.rank.median(image)
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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 accommodate different build environments 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
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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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if isinstance(matching, str):
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raise ValueError('``matching`` should be a list of strings and not '
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'a string itself.')
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# Special case for disabling the context manager
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if matching is None:
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yield None
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return
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strict_warnings = os.environ.get('SKIMAGE_TEST_STRICT_WARNINGS', '1')
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if strict_warnings.lower() == 'true':
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strict_warnings = True
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elif strict_warnings.lower() == 'false':
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strict_warnings = False
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else:
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strict_warnings = bool(int(strict_warnings))
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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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# Allow users to provide None
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while None in matching:
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matching.remove(None)
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remaining = [m for m in matching if r'\A\Z' not 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 strict_warnings and not found:
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raise ValueError('Unexpected warning: %s' % str(warn.message))
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if strict_warnings and (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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