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from __future__ import print_function, absolute_import

"""
Supporting isolation of warnings

Warnings in unittests are not isolated.
We sometimes use warnings to conveniently accumulate error messages
and eventually report them afterwards as error.
"""

import sys
import warnings
import re
from contextlib import contextmanager

warn_name = "__warningregistry__"
ignore_re = 'Not importing directory .*'

@contextmanager
def isolate_warnings():
    save_warnings = {}
    for name, mod in sys.modules.items():
        if mod and hasattr(mod, warn_name):
            save_warnings[name] = mod.__dict__[warn_name]
            delattr(mod, warn_name)
        else:
            save_warnings[name] = None
    yield
    for name, warn in save_warnings.items():
        mod = sys.modules[name]
        if mod:
            setattr(mod, warn_name, warn)
            if warn is None:
                delattr(mod, warn_name)

@contextmanager
def suppress_warnings():
    with warnings.catch_warnings():
        warnings.simplefilter("ignore")
        yield

def check_warnings():
    for name, mod in sys.modules.items():
        if mod:
            reg = getattr(mod, warn_name, None)
            if reg:
                # XXX We need to filter warnings for Python 2.
                # This should be avoided by renaming the duplicate folders.
                for k in reg:
                    if type(k) is tuple and re.match(ignore_re, k[0]):
                        continue
                    return True
    return False

def warn(message, category=None, stacklevel=1):
    """Issue a warning with the default 'RuntimeWarning'"""
    if category is None:
        category = UserWarning
    warnings.warn(message, category, stacklevel)

# eof
