# -*- coding: utf-8 -*-
""" recording warnings during test function execution. """
from __future__ import absolute_import
from __future__ import division
from __future__ import print_function
import inspect
import re
import sys
import warnings
import six
import _pytest._code
from _pytest.deprecated import PYTEST_WARNS_UNKNOWN_KWARGS
from _pytest.deprecated import WARNS_EXEC
from _pytest.fixtures import yield_fixture
from _pytest.outcomes import fail
[docs]@yield_fixture
def recwarn():
"""Return a :class:`WarningsRecorder` instance that records all warnings emitted by test functions.
See http://docs.python.org/library/warnings.html for information
on warning categories.
"""
wrec = WarningsRecorder()
with wrec:
warnings.simplefilter("default")
yield wrec
[docs]def deprecated_call(func=None, *args, **kwargs):
"""context manager that can be used to ensure a block of code triggers a
``DeprecationWarning`` or ``PendingDeprecationWarning``::
>>> import warnings
>>> def api_call_v2():
... warnings.warn('use v3 of this api', DeprecationWarning)
... return 200
>>> with deprecated_call():
... assert api_call_v2() == 200
``deprecated_call`` can also be used by passing a function and ``*args`` and ``*kwargs``,
in which case it will ensure calling ``func(*args, **kwargs)`` produces one of the warnings
types above.
"""
__tracebackhide__ = True
if func is not None:
args = (func,) + args
return warns((DeprecationWarning, PendingDeprecationWarning), *args, **kwargs)
[docs]def warns(expected_warning, *args, **kwargs):
r"""Assert that code raises a particular class of warning.
Specifically, the parameter ``expected_warning`` can be a warning class or
sequence of warning classes, and the inside the ``with`` block must issue a warning of that class or
classes.
This helper produces a list of :class:`warnings.WarningMessage` objects,
one for each warning raised.
This function can be used as a context manager, or any of the other ways
``pytest.raises`` can be used::
>>> with warns(RuntimeWarning):
... warnings.warn("my warning", RuntimeWarning)
In the context manager form you may use the keyword argument ``match`` to assert
that the exception matches a text or regex::
>>> with warns(UserWarning, match='must be 0 or None'):
... warnings.warn("value must be 0 or None", UserWarning)
>>> with warns(UserWarning, match=r'must be \d+$'):
... warnings.warn("value must be 42", UserWarning)
>>> with warns(UserWarning, match=r'must be \d+$'):
... warnings.warn("this is not here", UserWarning)
Traceback (most recent call last):
...
Failed: DID NOT WARN. No warnings of type ...UserWarning... was emitted...
"""
__tracebackhide__ = True
if not args:
match_expr = kwargs.pop("match", None)
if kwargs:
warnings.warn(
PYTEST_WARNS_UNKNOWN_KWARGS.format(args=sorted(kwargs)), stacklevel=2
)
return WarningsChecker(expected_warning, match_expr=match_expr)
elif isinstance(args[0], str):
warnings.warn(WARNS_EXEC, stacklevel=2)
(code,) = args
assert isinstance(code, str)
frame = sys._getframe(1)
loc = frame.f_locals.copy()
loc.update(kwargs)
with WarningsChecker(expected_warning):
code = _pytest._code.Source(code).compile()
exec(code, frame.f_globals, loc)
else:
func = args[0]
with WarningsChecker(expected_warning):
return func(*args[1:], **kwargs)
[docs]class WarningsRecorder(warnings.catch_warnings):
"""A context manager to record raised warnings.
Adapted from `warnings.catch_warnings`.
"""
def __init__(self):
super(WarningsRecorder, self).__init__(record=True)
self._entered = False
self._list = []
@property
def list(self):
"""The list of recorded warnings."""
return self._list
def __getitem__(self, i):
"""Get a recorded warning by index."""
return self._list[i]
def __iter__(self):
"""Iterate through the recorded warnings."""
return iter(self._list)
def __len__(self):
"""The number of recorded warnings."""
return len(self._list)
[docs] def pop(self, cls=Warning):
"""Pop the first recorded warning, raise exception if not exists."""
for i, w in enumerate(self._list):
if issubclass(w.category, cls):
return self._list.pop(i)
__tracebackhide__ = True
raise AssertionError("%r not found in warning list" % cls)
[docs] def clear(self):
"""Clear the list of recorded warnings."""
self._list[:] = []
def __enter__(self):
if self._entered:
__tracebackhide__ = True
raise RuntimeError("Cannot enter %r twice" % self)
self._list = super(WarningsRecorder, self).__enter__()
warnings.simplefilter("always")
# python3 keeps track of a "filter version", when the filters are
# updated previously seen warnings can be re-warned. python2 has no
# concept of this so we must reset the warnings registry manually.
# trivial patching of `warnings.warn` seems to be enough somehow?
if six.PY2:
def warn(message, category=None, stacklevel=1):
# duplicate the stdlib logic due to
# bad handing in the c version of warnings
if isinstance(message, Warning):
category = message.__class__
# Check category argument
if category is None:
category = UserWarning
assert issubclass(category, Warning)
# emulate resetting the warn registry
f_globals = sys._getframe(stacklevel).f_globals
if "__warningregistry__" in f_globals:
orig = f_globals["__warningregistry__"]
f_globals["__warningregistry__"] = None
try:
return self._saved_warn(message, category, stacklevel + 1)
finally:
f_globals["__warningregistry__"] = orig
else:
return self._saved_warn(message, category, stacklevel + 1)
warnings.warn, self._saved_warn = warn, warnings.warn
return self
def __exit__(self, *exc_info):
if not self._entered:
__tracebackhide__ = True
raise RuntimeError("Cannot exit %r without entering first" % self)
# see above where `self._saved_warn` is assigned
if six.PY2:
warnings.warn = self._saved_warn
super(WarningsRecorder, self).__exit__(*exc_info)
# Built-in catch_warnings does not reset entered state so we do it
# manually here for this context manager to become reusable.
self._entered = False
class WarningsChecker(WarningsRecorder):
def __init__(self, expected_warning=None, match_expr=None):
super(WarningsChecker, self).__init__()
msg = "exceptions must be old-style classes or derived from Warning, not %s"
if isinstance(expected_warning, tuple):
for exc in expected_warning:
if not inspect.isclass(exc):
raise TypeError(msg % type(exc))
elif inspect.isclass(expected_warning):
expected_warning = (expected_warning,)
elif expected_warning is not None:
raise TypeError(msg % type(expected_warning))
self.expected_warning = expected_warning
self.match_expr = match_expr
def __exit__(self, *exc_info):
super(WarningsChecker, self).__exit__(*exc_info)
__tracebackhide__ = True
# only check if we're not currently handling an exception
if all(a is None for a in exc_info):
if self.expected_warning is not None:
if not any(issubclass(r.category, self.expected_warning) for r in self):
__tracebackhide__ = True
fail(
"DID NOT WARN. No warnings of type {} was emitted. "
"The list of emitted warnings is: {}.".format(
self.expected_warning, [each.message for each in self]
)
)
elif self.match_expr is not None:
for r in self:
if issubclass(r.category, self.expected_warning):
if re.compile(self.match_expr).search(str(r.message)):
break
else:
fail(
"DID NOT WARN. No warnings of type {} matching"
" ('{}') was emitted. The list of emitted warnings"
" is: {}.".format(
self.expected_warning,
self.match_expr,
[each.message for each in self],
)
)
